On Sunday, the Washington Redskins will try to find their running game in St. Louis, where the Cardinals already have discovered the pleasures that can result from rushing efficiently.

The Cardinals, who once depended so much on Jim Hart's passing, have run for 203 and 231 yards the last two weeks. They've won both games to improve to 3-2, which puts them in playoff contention along with the 4-1 Redskins.

Washington has split its last two games, no thanks to an offense that has averaged 63 yards rushing. Defenses are beginning to gang up on quarterback Joe Theismann, who has had five passes picked off in that span after a streak of 96 straight attempts without an interception.

"I wouldn't say that all we are going to do is run the ball," Redskins Coach Joe Gibbs said of the 1 p.m. game (WDVM-TV-9, WMAL-63) that could be played in wet, cold, windy conditions. "We are looking for balance more than anything. When our offense plays well, we usually run for around 150 yards. That's what we need to get back to."

That's also the major difference between these teams' offenses. The Redskins, who are favored by a point, want to run and throw.

The Cardinals don't want to have to rely on the passing of inexperienced Neil Lomax or the protection of a massive but revamped offensive line. That line includes two rookie tackles and 288-pound tackle Dan Dierdorf at center.

"They are using Lomax just right," said Richie Petitbon, Redskins defensive coordinator. "He's a young guy who lacks experience, so they aren't putting a lot of pressure on him. Instead, they are relying mostly on the run, and then he fills in with a lot of key passes . . . "

Lomax, a former Portland State passing star who is in his first full year as a starter, represents a change for the Redskins' defense. He is the first quarterback Washington has faced this year who scrambles almost as quickly as he passes. He is big (6-foot-3, 215 pounds) and agile and, as Redskins safety Tony Peters put it: "He hasn't learned yet he can get his head knocked off by running around all the time."

Like the Redskins, the Cardinals are a team in transition. Half of St. Louis' starters have less than four years experience, including Lomax, a a first-round draft choice in 1981. Four others have been in the league only four years.

The Cardinals have tailored their offense to take advantage of Lomax's talents. He rolls out as much as he drops back, putting him in a better position to run. That means the Washington front four, already weakened by the loss of tackle Perry Brooks, has added worries. The Redskins have to stop halfback Ottis Anderson and keep Lomax in the pocket.

"We play a lot of man to man," said Peters, "and a scrambling quarterback really can hurt that coverage. You are watching your man and trying to keep an eye on him. When he starts scrambling, his receivers start improvising and things really can get choatic back there."

Redskins tight end Clint Didier, Lomax's favorite receiver in college, says his ex-teammate "can throw off one foot or offbalance or from almost any position you can imagine. I've seen him get rid of the ball when I didn't think he could."

This season, Lomax has thrown 116 passes, compared to Theismann's 140. Although Lomax has been sacked 16 times, he's been intercepted only once. He now has 72 passes without an interception. St. Louis has lost three fumbles. The Redskins have eight turnovers.

"We expect to see a lot of Anderson and (Stump) Mitchell running the ball," said Darryl Grant, who, as Brooks' replacement, may at times be the target of those runs. "If we can control them, it would give us a chance to put some pressure on Lomax. We want to have him pass a lot."

Anderson missed last week after experiencing chest pains following a 122-yard effort in a 23-20 victory over Atlanta. Mitchell, usually the Cardinals' punt returner, replaced him against Philadelphia and gained 145 yards in a 23-20 triumph.

Until late in the fourth quarter last week, the Redskins had stopped Dallas' running offense. The week before, the Eagles gained just 101 yards on the ground. Over the last seven games, no individual runner has managed more than 100 yards against Washington and only one team has gained more than 150.

To get their own running game moving, the Redskins likely will turn more to Joe Washington, who received his first extended playing time of the season against Dallas.

The Cardinals' defense has a new coordinator, ex-Lions coach Floyd Peters, who has brought stability to that unit. It has 14 sacks, but has been vulnerable to passing, giving up an average of 218 yards passing, 11th in the conference.

"We aren't going to forget about the pass," said Gibbs, whose team allowed seven sacks last week. "St. Louis normally isn't a blitzing team, but it wouldn't suprise me to see them try something after seeing the Dallas films. We still feel we can move the ball in the air, but what we want is consistency. That's how you win."