well ive posted befor but could not find the answer to my question and now my problems gotten worse....i have an 89 camaro v6 2.8 stick. And it ran good for the first weeks i got it. Then i would run is and it would stall while driving, i would be driving and it would just turn off. It backfired, or misfired lke crazy at undetermined times. sometime it reved up on it own at the rpm reader it would just rev up and down uncontrollably sometimes till it turned off....once it backfired and blew my muffler open. So i did the tune up, oil change, air filter, oil filter, fuel filter, i did new spark plugs and wires, and put in a new muffler. Then the car seemed to work great...that is till the next day when it did several backfires and eventually ripping open my new muffler. So i went back and replaced the timming chain, with the gears......the old one that was on, was sooooo lose. Then i put in a fresh one really tightly on their. The the car ran in perfect condition...it had lots of power considering its a v6 and compared to the way it ran before. it shifted nicely. but then it did it again and now they are severe backfires....again ripping another muffler! the problem only got worse, now thier is now power...and to get from one gear to another i have to really step on the gas its slow. when i finnaly make the gearshifts thie is a lot of jerking. Now this morning..i went out to go to work cranked the car and it started like always but then it just had an abrupt shut down. I have tried to turn it on but it only cranks but it wont turn. I put in a new starter, but it didnt help. just cranks but wont start. Please help me i love this car and i dont want to loose it. Im not very mechannically inclined but im trying my hardest cause i love this car.

this happens to
After some cranking, the motor turns over, idles for 3-10 seconds, dipping lower until it dies. If I give it gas, it stays running. If I give it gas right before it dies, it blows a backfire through the throttle body. If I rev it up to above 4K and lay off, it sounds like small backfires out the tailpipe as it settles back to idle. Also, after working on it and having it running stationary for about 45 minutes, the coolant is boiling in the expansion tank. please help me thank you

Sounds like a timing issue, check your spark plug wire to make sure they are on the right plug and check the spark timing as well, also recheck the timing chain and gears that you put on.