engine missfires and backfires

I have a 89 jeep Cherokee with 4.0l st8 six. The engine starts hard and missfires when running, like riding a bucking bronco. My son says his back is starting to hurt. I have the non-adjustable timing type distributor. The engine was rebuilt a couple months ago. The front-end was rebuilt as well as the transmission. The distributor's lockdown ear is broke off and a regular holddown clamp was installed. Does this mean I could actually turn the distributor like a normal one? It seems like the timing is off. I'm thinking multiple problems may be occuring. The engine starting hard could be a misaligned crank sensor. The backfiring could be timing or electrical. Any help will be appreciated, I have way to much money to give up on this thing. Selling it right now is useless since it won't run right.

I have a 89 jeep Cherokee with 4.0l st8 six. The engine starts hard and missfires when running, like riding a bucking bronco. My son says his back is starting to hurt. I have the non-adjustable timing type distributor. The engine was rebuilt a couple months ago. The front-end was rebuilt as well as the transmission. The distributor's lockdown ear is broke off and a regular holddown clamp was installed. Does this mean I could actually turn the distributor like a normal one? It seems like the timing is off. I'm thinking multiple problems may be occuring. The engine starting hard could be a misaligned crank sensor. The backfiring could be timing or electrical. Any help will be appreciated, I have way to much money to give up on this thing. Selling it right now is useless since it won't run right.

Take it back to whoever rebuilt the engine ,tell them to check the timing it sounds like it's advanced, causing the hard starting & the backfire, Have it checked before you do real damage to the engine, :banghead: [email protected]