93 Z28 Runs fine until she reaches op temp then starts to cough and hesitate,sometimes it get so bad that she shuts down. Will run fine down the freeway but after exit and a couple of stoplights problem arises.
New Ing module, Ing coil, wires ,plugs and air filter. Dealer says distribitor needs replacing but why would the distribitor only malfunction after a good run. Any suggestions greatly appreciated.

 

Could be your O2 sensors. If you unplug one of the oxygen sensors from the harness the car will run in a safe mode that doesn't use the O2s for A/F, if your problem clears up, look into getting new O2 sensors. Oxygen sensors for our cars are only like 20 dollars from Autozone since they aren't heated.

Hope that helps.

Edit: Also make sure you plugs are correctly gapped. I had some Bosche plugs in mine and it ran like hell even though they were new, regapped them and it still ran like hell, come to find out it was the plugs themselves. Switched to some Delco's and it ran fine.