I have a 97 Suburban 5.7 1500 4x4 and have changed out my dist cap and rotor, all pluge and wires, both cat converts and idol sensor. When I pulled my plugs #3 and #5 there was alot of build up. I spoke to a mechanic and he told me that I might have a clogged injector. I don't have the money or time to put my truck into the shop and I don't mind getting dirty fixing it. Does anyone have any ideas? Also, my 4 wheel drive is not responding. It was working just the other day now the lights on my 2 low and 4 low and high are not even on. When I press them nothing happens. Help please!