I have a 1992 Ford Explorer XLT 4.0L OHV. I just got done replacing my fuel injectors(remanufactured), TPS, valve cover gaskets; repainting my valve covers; and cleaning my fuel rail, upper intake manifold, and throttle body. Now the engine runs like crap. When the engine runs, I hear a loud occasional popping sound coming from the engine compartment (not sure exactly where but almost sounds like a backfire) every 3 to 5 seconds and the engine will shake like its a bout to die. The RPMs do seem a little below average for idle, but by barely a hair. Also, a very strong rotten eggs smell coming from the exhaust.I pulled all 6 spark plugs, and all three on the driver side of the engine were very black and sooty and one of them, the arc was actually bent a little (I would post images, but i don't know how to). The other three however, had normal wear. The spark plugs only had less than 1000 miles on them. So I replaced all 6 plugs in the hope that they were the cure, but no luck. I installed them and the engine ran no different. I ran the engine for a few minutes and pulled the plugs. The 3 on the driver side were already kinda sooty, and the other 3 looked fine. When I performed the KOEO test, all i get is 111, meaning all systems ok. When I performed the KOER test and goose test, all I get is 116 (engine coolant temp sensor out of range). Really confused at this point. The engine ran fine before I worked on it other than the leaking valve cover gaskets. Any help is greatly appreciated. Thanks! Also, when put into gear (auto trans) the engine dies.