Need some help. So a friend of mine has a 97 TJ with a 4.0 straight 6 manual transmission and norther friend of ours installed a new header back exhaust (magnaflow) and also replaced the spark plugs and distributor cap and the other friend didn't mark the wires for spark plugs. Found out after jeep wouldn't start. We believe we have them in correct order but now we are getting a backfire from intake manifold. No other issues. It idols at normal 900-1000 RPM's any help. We have someone that thinks it's something blocking the cat converter backwards
Any help would be appreciated.