I just recently installed headers on my truck and new exaust, After instalation I tested it out, and the truck ran like [censored], back firing and stalling. I found that I had cracked the porclin on one of the spark plugs. so I replaced it. Now the truck idles great, but has no power, significantly less than when I started. I dont think that the engine is getting enough fuel. I had taken my truck to school, and I could barly hit 70mph on a slight incline. and after 200 miles the truck started stalling. filally I left the damn thing in Hagerstown, MD and hoped in my girlfriends jeep. What the hell could it be!