NEW YORK (AP) _ Flamboyant rock singer Morris Day's idea of acting is to raise his eyebrows and purse his lips.

That makes him just perfect to play flamboyant record producer Curtis Rousseau in the NBC sitcom pilot, ''Heart and Soul.'' NBC is airing the show Thursday in place of ''A Different World.''

Rousseau's foil is Richard Bradley, the reasonable, right-thinking half of the partnership. He is played by Clark Johnson and lifts the sitcom above insulting stereotype level.

Richard wants to quit the business to teach high school music. Curtis is appalled - ''We've been together since Michael Jackson had cartilage'' - and thinks a new girl singer he has discovered will change Richard's mind. But her rather large, conservative father, played by James Avery, thinks record producers are a sleazy lot and prefers that his daughter go to medical school.

To convince the father otherwise, Curtis makes a stab at respectability by donning a three-piece suit. Checking himself in the mirror, he notes, ''If there was a charity for people who had to dress like this every day, my check would be in the mail.''

Day doesn't deliver lines very convincingly, but his personal style is often delightful, as when he pirouettes to pick up the phone, or whoops his pleasure at the outrageous compliments dished by his mailroom sycophant (Barry Sobel): ''They said Elvis was de king? He not de king. You de king 3/8''

But the second half of the comedy turns to leaden melodrama when the aspiring singer (Tisha Campbell) tries to persuade Richard to manage her career. When she finally sings, she has a great voice, but the scene is embarrassingly maudlin.

One of the executive producers of ''Heart and Soul'' is Quincy Jones, Michael Jackson's producer. With some inside-the-business insights and a few more laughs, this show might have given Jones a different kind of hit.

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WHY IS THIS MAN HERE? - John Candy seems pleased but vaguely perplexed about why he was chosen to be host of HBO's live special from the Just for Laughs International Comedy Festival in Montreal on Saturday.

The festival features mostly standup comics. Candy, a former cast member of ''SCTV,'' is a comic actor, but he's never done standup.

''They had called way out of left field,'' he said. ''I'm not really associated with standups at all, so I don't understand. But I was flattered. I do have a great respect for these people.''

The festival began six years ago as a French-speaking event, but has expanded into a 10-day, multilingual festival. This year's headliners include Richard Belzer, Steven Wright and Graham Chapman.

Candy is Canadian, but he hadn't been to the festival before, and is therefore a somewhat diffident salesman for the event, even though HBO arranged an interview to promote the special.

''They're spending a lot of time, money and effort there,'' Candy said, searching for something promotional to say. ''They seem very organized. There's a lot of great acts, judging by what I'm seeing. It's very impressive, and it's got a big guest list there.''

Candy was a little more forthcoming about the movie he was shooting in Toronto. He described it as a detective comedy a la Peter Sellers' Inspector Clouseau.

Except for ''Splash,'' Candy's movies haven't been roaring successes with the critics. He's currently starring in ''The Great Outdoors'' with Dan Aykroyd.

He insists, though, that he's very happy with the script for the new movie, which is being directed by Paul Flaherty, brother of Candy's SCTV colleague Joe Flaherty.

''I rarely talk about movies I'm in, but I feel very good about this one,'' said Candy, who is its executive producer. ''It's got a nice feel to it. Very reminiscent of some of our work on 'SCTV,' you know, creative periods where you can just feel it, sense it, good work.''

Candy said he's tired of dealing with movie people who ''know nothing about comedy'' and just try to get the movie out as quickly as possible.

''I'm tired of it, and my associations in the future will be with people I feel I can depend on and trust,'' he said. ''I'm looking at my pictures a little more carefully now. If the odd cameo comes up, you've got to look out for money, we all have to make a living. But the ones I'm involved with, if you know what I mean, I want to make sure they're done right.''

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Elsewhere in television:

JULIANNE REDUX - All the brouhaha over the bust-up of Bruce Springsteen's marriage has died down, but confused or merely curious viewers can get a look at the rock wife in question when NBC reruns ''His Mistress,'' a made-for-TV movie starring Julianne Phillips and Robert Urich on Aug. 1. Urich plays a corporate big-wig and Phillips plays the title role. The movie originally ran in 1984, the year before Phillips married Springsteen.