I just changed the head gaskets. It starts right up and runs fine. But when it warms up and I put it in drive the engine gradually starts to hesitate within 30 seconds in drive it hesitates the most and stays there...until I turn it off and let it cool. Once cold it starts all over again, runs fine then hesitates. I redid the valve lash a couple times, then I changed the spark plugs, but the problem is still there... any ideas?? it doesnt hesitate if I warm it up in park and rev the engine

 

anyone?

 

Check for vacuum leaks after car is hesitating spray WD-40 around intake manifold and see if hesitation goes away. make sure all vacuum lines are attached.

 

turns out I set the valve lash waaay too tight...that would explain it..runs great now