I have an 89 Pontiac Firebird, went on vacation for a month wife drove it and didn?t check the oil so soon enough bye bye motor. Had a garage find a motor that they said was in good condition but they sent it to a second garage to do the actually installation. We got the car back and it was running rough. At high rpms (2000+) it would jump and stutter like mad, and when you stopped at red lights it had a tendiousy to jump from 700 to 1500 rpms then sputter and the engine shut off.
I took it back to the garage that put the engine in they had it in their shop for three weeks and when we got it back it wasn?t as bad but it is still very far from working. They changed the distrubter, the coil, and ran it on the computer a while but the garage employee/owner isn?t completly reliable and i mainly took my car there becasue his father owned it and he was a good mechanic...but has recently retired.
So me and my father have since replaced/adjusted the throttle positioning switch, the air intake valve, checked the timing, and took it into the shop where we work and had the mechanic there put it on the computer, other then a rich fuel message the computer didn?t give back any other codes. For a couple days however it began to run smoother and smoother and while i was out running it to see if it was going to finally work itself out i noticed white smoke coming over the hood (oh joy!) so i pulled over opened the hood it was fine, looked under the car and saw my big puffy cloud, the radiator pan seal was shooting out fluid and making it land on my muffler/cat.
The muffler and cat are also newly installed. The car now stutters around 3k, when i stop at a red light for to long it will now not stutter and shut off but will simply shut down completly without warning. The car isn?t making any strange noises other then one i smash it with the sledge hammer (well it will soon)...please hellppp