One of the main problems with these motors is the head gasket, they will go bad but not totally blow out. Check your compression thats how I found mine was bad. Also if you have the stock intake tube on it take it off and check to see if it has a hole in the bottom, it runs across the air pump rail and the heat will burn a hole in that rubber tube, now your pulling air after the MAF sensor. I had both issues on mine and it wouldnt idle worth a shit and if you cracked the throttle it would die or start backfiring. Good luck!