1991 Chevy Corvette Hesitation

This is a ZR-1. Whenever the throttle is pressed anything more that the lightest touch, the car hesitates. Sort of stutters, before accelerating. This occurs more when warm, but also haoppens cold. So far I have had a full tune up, new injectors, plugs have been changes twice, new wires. The computer at the dealer says all is well.
My mechanic found a "sensor" that was reading the engine temp 20 degrees too low. He changed that but it didn't solve the problem so we took it out.
The only other oddity is that the heat doesn't work. I have changed the thermostat but still no heat. One would presume that, if both problems started at the same time, they have a common cause.