fuel problem

[dre240]

about a week ago , i bought gas from cumberland...bad idea. the next day i was in my car and the rpms droped and the call shut off. i couldnt get it to start and it seemed like a fuel problem. i then bght gas teatment and th car started. the idle is very rough and when i hit about 3k rpm the car jurks back and forth. i changed the fuel filter and the spark plugs. the plugs were charcoaled. i was hoping that worked but its still riding rough. the car is smoking a lot ...black smoke. dont know what should i do next. on stock boost when i get on it a little it back fires a lott. on high boost its scarey. any HELP would be appreciated. i really need help.

[scottsnissan]

did u do anything else beside drive.(get on it before it stoped).Sounds like ur running real rich.Could be a boost leak or something.

[dustyk]

I agree that it sounds like a boost leak. Ive never heared of bad fuel causing the engine to run that rich (Usually bad fuel just causes the knock sensor to go crazy). Most likely you have a vacuum leak. If you have a boost gauge, how much vaccum are you pulling when you are at idle? Check your intercooler piping and vaccum lines for any leaks.