My truck was running perfectly until one morning I started her up and the rpms sky rocketed to 2500 rpm and the exhaust fumes emitted were somewhat dark and almost smelled like natural gas. The CEL came on and then the rpms dropped to 1300ish rpms. I pulled the codes on my ‘94 5.8 and got: 654, 10, 128, 212, 111 (in that order). To be as helpful as possible I will mentioned that I recently installed led bulb taillights, led headlights, and swapped out the dash bulbs for green leds (she was running perfectly after for several days), don’t know if this might have something to do with it. I looked up the individual codes but I would like some suggestions and opinions as to where I should begin, don’t know what to test first. Sad part is this just happened after I was getting my truck ready for the lift kit Any help is greatly appreciated, thank you guys.