okay guys i have been trying to trace this problem. around 4,000 rpm when wot the car backfires through the exhaust i think. when not in gear and I rev it no backfire.I am trying to figure if this is a vaccum leak or injector. i am also getting a missife cylinder 3. so in changed the spark plug and no diffrence. i have deltec and new plugs and wires. so my best guess would be bad injector on cylnder 3. so i unplugged it and it just started missing alot. any other way to test injector without putting a new one in? thanks guys

 

anyone??

 

anyone?