95 Montero 3.0, misfire or valve problems?
 

95 Montero Ls with 3.0 6g72, auto trans

Started about 3 weeks ago. At first thought it was a torque converter problem. Would shudder from stop to going, and shudder when it locked at low rpm.

Problem progressed enough it is clearly engine problem, at first I thought it was a miss perhaps. At an idle i can open throttle and it misses and pops at first and then cleans up at higher rpm, however as soon as i let go of throttle it backfires as the rpm's go down and shakes. However when driving especially at low rpms, if you give it anymore then slight throttle it shakes and you can hear it going "thud thud thud thud thud thud" (thats not the most accurate description), and it will surge forward and then slow and surge and slow, and well you get the idea.

It gets worse almost everytime i drive it, at first it would only do it a little, now it does it no matter what speed or rpm i am at, does it an idle now too.

I replaced spark plugs and wires last year, i took apart everything and looked at spark plugs and they appeared healthy. I don't have very much money to throw at this, and my experience with problems like these are limited. My guesses are either weak ignition coil, bad spark plug, bad MAF, or possible timing is off ever so slightly. I don't really know thats why i am asking.

get a compression check done.

I have had a few cars with this symtoms. it turned out to me the fuel filter. my 81 corolla did it and my 69 roadrunner with 2 carbs and all built. same problem and its really cheap to fix and if its not it it done hurt to change it.