Have a 90 gt that we just replaced the motor. Motor seems to run great after sitting for 8 years. The only problem I'm having is it runs rough when you first start it, clears up after a couple of minutes, like someone flipped a switch. Then if you cut it off and start it, it does it all over agian, every time. I've checked sensors, you can disconect them and it clears up also but the check engine light comes on. I replaced the air charge temp sensor, made no difference. Like I said you can unplug the sensor while it runs rough and it clears up, so I'm thinking it's in the system some where. The time it runs rough seems to be exactly the same. Any ideas as to what might be causing it to do this would be appreciated.