91 tracker won't start popping sound from engine

OK new problem, car starts but then dies after a popping sound comes from the engine, sounds like a backfire, but its coming from the front of the car! Car seems to turn over and catch but won't hold. Still bad fumes coming from exhaust, bogs at idles and then idle runs really high. Compression problem?? Everytime I take it to mechanics they don't seem to know what the problem is! Been reading about carbon buildup, could it be that? or possibly a exhaust problem. Any help would be truely appreciated.

Look at my post and I've had your problems too... Yes... check your compression...youll need well over 100 to start your car consistantly and when it's raining. At factory marks on cam and crankshaft, check to see if your piston at TDC is begining its downward decent by feeling with a wooden dowel inside that pistons spark plug hole ... this is in my opinion a better way of timing your car and not solely relying on your marks or even a way to decide which way to go if your halfway inbetween teeth when putting on your timing belt. In my case i went almost 2 teeth back CCW on the crank while leaving the cam centered on mark. Bam... I went from 70psi to 150psi. I'm at a total loss to explain why this works so well. What's up with that? Is a tracker a car made to fire after true top dead center?