Revs smoothly in park, but

when idling in drive it has these quick hesitations about 4-7 seconds apart, like someone bumped into the back of our car very lightly. I guess I should check spark first. bought it 7 months ago(smallest engine: 1600). The Distributor cap and wires look fairly new.(the concensus is to bite the bullet and buy the cap and wires from Toyota, which I have been doing, but it’s now $130 ouch! If you can help, thank you… Mike

Did you ever replace the fuel filter?

Haven’t had the car very long but that’s a good place to start - thank you…Mike

Just go ahead and do all the basics. New plugs & wires and filters. Clean the throttle body and MAF sensor.

I’m not familiar with MAF…something air flow ?

This engine system doesn’t use a MAF (Mass Air Flow) sensor. I have the same engine in my '92 Celica. A thorough throttle body cleaning would be a good idea, though.