For a little-known congressman from Illinois, Philip M. Crane was doing surprisingly well in his "early bird" presidential campaign. He had raised almost $2 million, more than any of his fellow Republican opponents.

He was drawing attacks from supporters of GOP front-runner Ronald Reagan who saw Crane as a threat to the Reagan constituency. And he seemed to be stirring up early support in Iowa, New Hampshire and Florida, the sites of three early tests of the 1980 election.

But then things went sour.

First came money problems, and a break with his chief fund-raiser, Richard A. Viguerie. Then came a messy power struggle over the control of his campaign, with Crane's wife, Arlene, accusing his three top aides of being a "devil's triangle." Then, his entire senior campaign staff resigned, with his campaign manager declaring that Crane lacked "the commitment or capacity to wage the sort of campaign necessary to win."

But that wasn't all.

Almost every day for the last week some new peril has visited Crane, giving his campaign a Keystone Kops air.

One day, an offhand remark by his new campaign manager, Jerry Harkins, that if Crane falters in 1980 he always has 1984 to look forward to, led to speculation in some conservative circles that Cranes might pull out of the campaign early.

Another day, Crane, hearing reports that a list of contributors was missing, called in the FBI to investigate. (The list turned up where it was supposed to be in campaign headquarters.)

And yesterday, Crane learned that Harkins had been an unindicted co-conspirator in one of the largest stock fraud deals in Iowa history.

Outwardly, Crane yesterday appeared unconcerned about the report concerning Harkins. If he'd known about it, he said, he still would have appointed him campaign manager.

Harkins, 50, said it never had occurred to him to tell Crane about the 1976 case, in which he was said to have conspired with a business associate, John Howes, to make false representations about securities being sold in Iowa.

The case never came to trial, because Howes pleaded guilty to another charge. "I had actually forgotten about it," Harkins said. "It was like I had gotten a parking ticket."

The Des Moines Register, which reported the case in yesterday's editions, quoted sources in the Iowa attorney general's office as saying that Harkins had not been indicted and brought to trial because he had agreed to testify against Howes. Harkins called the report "a total lie."

Every campaign, of course, has its problems, its internal battles and growing pains.Seldom, however, is the dirty linen washed in public in the manner of the Crane campaign during the last week.

In his campaign headquarters near Bailey's Crossroads, Crane yesterday expressed genuine puzzlement on how what may turn out to be the unmaking of a presidential campaign all began.

The chief players in the unfolding melodrama.:

Crane, a fourth-term conservative congressman from a suburban Chicago district, and his strong-willed wife, Arlene. Crane, adopting a strategy similar to the one President Carter used to win the presidency, became the first Republican to enter the 1980 race officially last Aug. 2.

Richard Williamson, Crane's campaign manager, former administrative assistant and closet political adviser.

Richard A. Viguerie, the well-known direct mail expert and a leading spokesmen for what is called the New Right. By March 30, he had raised $1.7 million for Crane's campaign.

Arthur Finkelstein, a leading Crane pollster and hired political consultant, and a group of aides Finkelstein had brought into the campaign, including its executive director, Tony Palladino.

A group of Crane's old friends and relatives, including Harkins and Rep. Daniel Crane (R-I11.), his brother, who became concerned about how the campaign was going.

Everyone involved in the incidents agrees that the trigger incident was the May 3 resignation of Williamson, the chief architect of the campaign.

Crane and his wife had just returned, tanned and refreshed, from a week in Hawaii. Severe problems within the campaign had been brewing for about six weeks before he left. Crane, however, apparently underestimated them.

Many of the difficulties have previously been reported as ideological conflicts over whether Crane was deserting his conservative background to run more as a mainstream candidate. This now appears incorrect. The real conflict was over the control of the campaign.

The initial problems were money and Viguerie's role in the campaign. As early as Jan. 5, Williamson and Palladino became concerned that the Viguerie operation was not bringing in enough money to justify its cost. During the next three months, they held 16 separate meetings over the Viguerie matter, keeping Crane informed of the progress.

The first public indication of any problems, however, didn't emerge until the campaign filed its spending report with the Federal Election Commission last month. It showed that Crane had spent $2 million to raise $1.7 million, and that his campaign was $880,000 in debt, with $461,000 owed to Viguerie.

Viguerie argued that the debt was a reasonable one to expect at that stage of the campaign, and urged the campaign continue "prospecting" for contributors with mailings to known conservatives. Williamson and company argued that costs were getting out of hand.

On April 6, Crane sent Viguerie a letter ordering him to stop operations. A computer was then brought into Crane headquarters to do fund-raising. On April 24, Viguerie retaliated with a letter, charging that Crane had violated their contract and threatening legal action.

Meanwhile, other, perhaps, more severe problems, were festering. Field workers were finding it difficult to communicate with the topheavy campaign headquarters in Washington. Top campaign aides were finding Crane difficult to reach, and unwilling to make decisions. Arlene Crane was fuming.

She started calling Finkelstein, Williamson and Palladino "the devil's triangle."

"They were a bad combination," she said yesterday. "There was no follow-through at headquarters. People kept calling and writing to me. It wasn't what they were doing. It was what they weren't doing."

Williamson, Palladino and Finkelstein felt their authority was being undercut, and that the campaign had become bogged down in minutiae. At one point, Williamson threatened to resign.

On May 2, he repeated his frustration at a campaign staff meeting, and said he intended to resign the next day unless something was done. Palladino arranged a meeting with Crane for the following morning.

Crane didn't go to the meeting. He said he thought it was just going to be about the Viguerie issue, which he thought he had resolved in a series of telephone conservations with viguerie.

When Williamson hadn't heard from Crane, he sent his secretary to his congressional office with a letter of resignation. Crane promptly appointed Harkins, who had come into his 1969 congressional campaign when it was in trouble, to head the new campaign.

That night all of Crane's top campaign staff, except his Florida, Midwest and New England coordinators, resigned in sympathy with Williamson.

"Their loyalty was to Rich. He had hired them," said one staff member who stayed. "Lots of them didn't even know Phil."

"Basically, Phil decided to let his wife run his campaign," Williamson said.

Crane and his old associates insist that the campaign will go forward, stronger than ever before. Others disagree. CAPTION: Picture, REP. PHILIP M. CRANE . . . appears outwardly unconcerned