You might also try the coolant temp sensor ( I think it's mounted below the distributor). It is not the one that drives the gauge on the dash. It's the one that tells the computer that the coolant (and engine) are at operating temperature. If it fails, then the computer starts adjusting the timing as if the engine was cold. Goofy things happen. This did the trick for me several years ago.
Like Cousin It stated...Cleaning the IACV is a good idea too. (Idle air control valve) both problems will cause similar symptoms.

Good luck.
dan