I cant figure out what is causing my check engine light to come on. Car runs good. Starts a little slow and kinda sputters when first starts. Usually engine light comes on when the car shifts into 4th gear for the first time in the morning or after work. But after its warm it will not come on. The car is an automatic. I changed the o2 sensor, coolant temp sensor and map sensor. My gas mileage has dropped from around 400 miles at least per tank to about 320-350. Any ideas please let me know.

 

What code is being set/stored? I'll assume this is a 95 by your name, if so there is a service connector on the pass side you can short and then count the flashes of the the CEL/D4/ABS (if it has it).

 

I will try and look for it. The car doesn't have abs.