Major problems

[bigred90gt]

I've got big problems and don't know where to start. At low rpm's, and sometimes all the way through the rpm range, the car putters like it is misfiring. I thought it might be the timing, so I went to have it adjusted. When they adjusted it, I hit the gas, and it started popping(like a backfire) sporadically. The guy put the timing back where it was and said I have bigger problems. Lot of help there. When I pull the plug out to set the timing it is fine, but when the plug is back in that is when it gets really bad. Once the car gets warmed up, the engine starts to sputter at idle and dies. When stopping at a redlight, I have to put it in neutral and ride the brake with my left foot and the throttle with my right to keep it from dying. When I try to re-start it, it acts like it doesn't want to turn over. If i stay in the starter, it'll crank, eventually, almost like a dying battery. Also, when I get on it, the rpm's increase, alot faster that the speed. At idle, it sounds like something is rattling around in the tranny. But when I push the clutch in, it stops??? I have got to do something, my truck is missing 1st and 2nd gear and I have had to drive my mustang as a dialy driver. If it goes, I'll be up a creek without a paddle. Please help, I'm at a deadend.

I have already changed the plugs, cap and rotor, and the O2 sensors. That did nothing. My check engine light won't go off either. When I replaced the O2 sensors, I disconnected the battery for 20 min's and when I cranked it back up, the light was still on.

Any and all suggestions would be greatly appreciated. I have a feeling it is just a matter of time before I am without a ride.
Thanks in advance for your help!!!