If I remember correctly the engine has to be at operating temp and the TPS disconnected. Note: It will not want to run at idle at first so you have to hold the RPM at around 2K and slowly let it down. Then you may check the timing. This is the Baseline setting or whatever the FSM says it is.

It would not be uncommon to have a little advance with the TPS hooked up and a miriad of other conditions, but if you've turned the Dist at all, I would perform this check to make sure it is right. The ECU can only compensate so far from the Baseline, then run into trouble.

Good luck, I'm changing the engine clutch fan out for electrics (2 on the Condensor and 1 on the radiator) and hope that will give a little bump on HP and MPG, but I don't expect much. I will however get cold A/C all the time.