Something unsavory stews in Europe: rancorous shouts against an American president's reiteration of long- established NATO strategies, "peace" demonstrations singling out the United States for special abuse and rebuke, orders to shape up our economy from President Francois Mitterrand, whose own vision of economic rectitude is drawn from the socialist flapdoodle of Dr. Marx. From the prime minister's office of Andreas Papandreou in Greece to the parliamentary benches of Britain's second most powerful party--all over Europe, wherever the forward-lookers gather, the pot bubbles and brews with anti-Americanism.

Of course, it is difficult to measure the exact dimensions of it all. Indubitably there is a vast affection for things American among ordinary Europeans, especially European youth. Moreover, there are European pols and businessmen who think of us with affection. However, among the majority of European exalt,es a disrelish for things American is always in the bloodstream.

"There is a terrible European habit of patronizing Americans," admonishes the English journalist Edward Pearce, "an assumption of universal-rich- homicidal-half-wittedness among them." And he goes on in this month's Encounter magazine to observe that anti-Americanism is not restricted to the Europeans. He has spotted it among our cisatlantic liberal brethen, too. Pearce has a jeweler's eye.

Anti-Americanism exists on both sides of the Atlantic, and today this stew of egotism, envy and malevolent prejudice is turning the afflicted into a ravening herd. Michael Foot, the leader of England's Labor Party, is a splendid example. Admittedly, he is not a very thoughtful man or even a very peaceful man, but mere bloody- mindedness will not explain his crazed response a week ago Sunday to President Reagan's perfectly accurate summation of NATO strategy. Foot termed it an "insanity and an outrage." He never talks this way about that idealistic nation to the east, the one that aims SS20 missiles toward his countrymen. But then the Soviets never debauched his people with Coca- Cola and the Marshall Plan.

A more bizarre example of anti- Americanism is the anti-Americanism that fevers those members of the American press corps who have dwelt among pretentious Europeans too long. Consider the American reportage of the Oct. 25 anti-nuclear demonstrations in Paris. "Fifty thousand chanting men and women, some wearing gas masks and others in skeleton costumes, marched through chill, rainy Paris streets today," reported Frank J. Prial in The New York Times. That figure of 50,000 and even higher figures were reported by every American correspondent that I have thus far discovered.

The figure is a humbug. Paris police reported only 5,000 demonstrators. Even the sponsors of the demonstration, the communist-dominated French peace movement, counted only 25,000 marchers. Furthermore, the demonstration was not the ominous affair Prial and other American correspondents reported. It was a flop. Veteran students of French politics, such as Jean-Francois Revel, and most of the French press termed it a flop, and some, such as the left-wing Le Nouvel Observateur, denounced it in terms redolent of Al Haig at the height of his powers: "This demonstration has become an important asset in the Kremlin game to the extent that it saps from within the 'Western consensus.' In the new Cold War this is another place where Soviet 'superiority' is evident."

Nonetheless, two days after the event, readers of the American International Herald Tribune read that "France, previously untouched by the spreading anti-nuclear movement in many European countries, has plunged into the international debate about Western rearmament policies, according to diplomats and French officials." Plunged? How can one account for such absurdity? We can explain The New York Times' faulty story by noting that their reporter is a recent emigr,e from that paper's culinary page, where he wrote movingly on the drama of the French grape. As for the others, well, I lay it to the anti-Americanism of the "diplomats and French officials" that they frequent.

In truth, the perverse consequences of European anti-Americanism are going to prove exceedingly dangerous for Europe unless Europeans throw off this bigotry very soon. Already there is talk in America of letting the Europeans go it alone. One hears it among politicians, and one hears it from the heartland. As William Safire made manifest in a column last week, even cosmopolitan Americans are growing impatient with European perversity. Some are beginning to think Sen. Mike Mansfield was right: perhaps we have invested too much in Europe.