I was driven down the highway at 70 mph when car started coughen and chuggen, i took the next exit and it died. it started right back up so i limped it to the nearest parking lot. As i got in the lot itkilled again so i coasted to a parking spot. I towed it home and here is what it now does; When i crank it it starts up right away but coughs and chuggs and dies after a few seconds with a big puff of smoke or gas coming from top of the throttle body. seems like it is almost getting to much fuel?? injectors are deffinently firing, i thought maybe i didnt have good enough spark so i put a diffrent distributor and coil in, didnt change a thing, if i unplug the injectors and crank it over it will run a little while on residual gas, and after that if i hook the injectors back up it will run good for 20 seconds or so then back to the same thing. its ran great for 3 months now until this. any help wound be great, thanks. 1990 camaro 350 tbi.

 

Ive owned 4 thirdgens, so I have encountered alot of problems in the past hehe, I had a camaro that did something like that, it stalled out, started right back up and on the way home I could floor the thing and only get it to like 30 mph, stalled at home would start then stall after a few seconds...to make a long story short, end up replacing everything from fuel rail, plugs, distrib, ecm, only to find out my cataylic converter was plugged cut the exhaust before catalyic conv and the thing started right up and ran like a beast Your problem sounds soo much like the catalyic converter.

 

I had some problems like that when I blew a head gasket.