Mitsubishi Repair: motor problam, piston rings, mitsubishi eclipse

Question
Hi i have a 1990 Mitsubishi eclipse 2L turbo and i just had the engine rebuilt, the machine shop cleaned it all but i had put it back together. now for the problem when i put it back together when i start it the idle is fine but when u rev it up the rpms drop to about 200 then 500 then 200 again it does this for a bit then shuts off. I did a compression test and #1 was 30 #2 was 145 #3 was 90 and #4 was 30, the pistons and piston rings are brand new and also i noticed that there is hardly any pressure coming out of the exhaust pipe the first time i thought it was the piston rings and the head gasket so i replaced them but it still does it, if u could help me that would be great. thanks

Answer
Matt: Your car falls in the right year for the bad computers. You of course have to know the computer controls everything along with many sensors. But Mitsubishi farmed out the building of their computers to another company that did not build very good ones, a piece will start to leak into the computer and with time will kill off the computer. This shows up in all kinds of different ways, as to whatever the piece leaks on. So some of your car's problems could be from a bad computer or even some sensors. I know, you will say the check engine light is not on. Well sometimes that light comes on and some times not. If nothing else you could have the car coded and rule out any problem with the computer or the sensors. I do know new rings have to seat themselfs in a motor. Or could be the rings are not on the pistons right. I am only giving you some ideas, I shall check with other people that work on cars and see what I might find out for you. I do hope this helps some and good luck! ~Linda~