1991 Pontiac Firebird

Engine Performance problem
1991 Pontiac Firebird V8 Two Wheel Drive Automatic 265000 miles

ok here it goes ive been chasing this problem since I had the car painted last year. I guesed it was the ignition timing because after I had it painted I drove it home and all of a sudden as I was accelerating normaly through the lights and it rolled back a bit and then jerked forward spinning the tires, that hasent hapened since but its been shaking like crazy lately after I timed it I used the light and the timing mark was jumping from 8degrees up to 13 and im thinking this isnt going to be too acurate so I did it by ear and got it running nice and it wasnt shaking too bad anymore, but oddly I was driving it home and it started geting rougher and rougher and loosing power by the minute until I made a turn and accelerated when it suddenly just cut out and sounded and felt like it was running on about 2 cylinders. I shut it of and tryied to start it again but to no avail it sounded like its not geting any fuel but it wanted to start which is odd because a day prior I had an oil pan full of fuel. My engine is a rebuilt 350ci l98 with tpi with either a 700r4 tranny. The rebiuld was done before I bought it and aparently theres something like 8k kms on the motor. Its running a shift kit, bigger cam which ive never seen so cant tell you the grind, k&n oem replacement filter, ngkr vpower plugs, new wires, cap and rotor, plugs, coil, hypertek stage 2 thermomaster or waterver its calledchip, 160 thermostat, factory intake box and manifold.
March 28, 2009.

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