Yea I dont see how you could mess up the plugs unless you took all the sheething off the injector harness. If you hooked them up wrong the car probably wouldnt run at all, but since I have never done this im not sure. Could you post a pic of your spark plugs numbered with the cylinder they came out of. Seeing the plugs makes diag much easier. You might just be running excessivly rich, which would definatly foul the plugs.