I have a 96 honda accord 2.2 L vtec. The engine had 143,000 miles and the timing belt snapped, so instead of having it fixed i bought an engine with 38,000 miles and swapped them out. The old engine ran fine before the timing belt snapping and the engine i put in it ran good when it was pulled. The car fires up and runs but from 1200-1700 rpm it lobes. it drives basically like the gas pedal is an on off switch, i'm either accelerating or decelerating but if i try to hold the gas pedal to where i can maintain one constant speed, it jerks back and forth violantly and feels like your riding with someone that has never drivin a stick before. It is also throwing a code for iac and iat but i swapped those out and that didn't fix it. I also swapped out the throttle body with the tps and that didn't fix it either. Any ideas??

 

Check all of your connectors and see if you swapped any, specifically TPS and MAP....and IACV and IAT. This happens ALL THE TIME.