The PCM is clean and has no corrosion, and tried tapping on the MAF sensor before testing it with a meter. So far I"ve changed fuel filter,fuel pump, cap, rotor, plugs, wires, pcv valve, water temp sensor, thermostat, 02 sonsor, ignition coil, and tested and or checked cat. converter, throttle pos. sensor, PCM, Maf, and fuel pressure is where it should be. Now when it does act up the check engine light comes on and it starts puffin smoke. And at one point the check engine light would flash on and off in about 3 sec. intervals and the truck would bog down when it came on. I'm not a mechanic but have done all our vehicle maint. for the last 18 years and this is first time had one down this long.