2002 Tahoe Dropping Cylinder

UPDATE. The truck has started missing again. I can unplug the rear passenger side coil and it makes no difference in the miss at idle. I checked the plug for spark and the coil and both have a very strong spark. The service engine soon light is still on and blinks occassionally. Here is what I have done so far, plugs, plug wires, fuel pressure regulator which was nearly impossible to get locally, fuel filter, O2 sensors, oil change, cleaned the MAF, checked for vacum leaks, sprayed the intake base to check for leaks, cleared the codes. I am baffled. Anyone please help. UPDATE. The truck has started missing again. I can unplug the rear passenger side coil and it makes no difference in the miss at idle. I checked the plug for spark and the coil and both have a very strong spark. The service engine soon light is still on and blinks occassionally. Here is what I have done so far, plugs, plug wires, fuel pressure regulator which was nearly impossible to get locally, fuel filter, O2 sensors, oil change, cleaned the MAF, checked for vacum leaks, sprayed the intake base to check for leaks, cleared the codes. I am baffled. Anyone please help.

It idles rough most of the time but will occassionally smooth out. Is this typical of an injector? I have also been told possible fuel pump. It idles rough most of the time but will occassionally smooth out. Is this typical of an injector? I have also been told possible fuel pump.

I am seeing alot about the MAF. It makes more sense that it would be the injector though as it until now was singled out to one particular cylinder. I was just out side and tried unplugging the said cylinder coil and the rough idle did not change. I then plugged it back in and went to another cylinder on the same side of the engine and unplugged that coil and the idle seemed to stay the same. Is it possible that the first coil I unplugged picked back up when I unplugged the next cylinder? If that is the case could that indicate the MAF? One more thing to add, It has recently been negative 25F here. When the truck sets overnite and I start it in the morning it fires right up, but does idle rough. I let it idle yesterday morning for about 35 minutes and when I got in it was idling smooth and after driving about 1 mile it started to idle rough. I have also noticed that after driving for a while and engine is at normal op temp it is hard starting. I am seeing alot about the MAF. It makes more sense that it would be the injector though as it until now was singled out to one particular cylinder. I was just out side and tried unplugging the said cylinder coil and the rough idle did not change. I then plugged it back in and went to another cylinder on the same side of the engine and unplugged that coil and the idle seemed to stay the same. Is it possible that the first coil I unplugged picked back up when I unplugged the next cylinder? If that is the case could that indicate the MAF? One more thing to add, It has recently been negative 25F here. When the truck sets overnite and I start it in the morning it fires right up, but does idle rough. I let it idle yesterday morning for about 35 minutes and when I got in it was idling smooth and after driving about 1 mile it started to idle rough. I have also noticed that after driving for a while and engine is at normal op temp it is hard starting.

Last Update. I have cleaned the MAF and no change. I unplugged the MAF and the engine sputtered once and then went back to running just like it did before I unplugged it. I then decided to see just how much I could unplug with out it changing anything. I unplugged the MAF and the new fuel pressure regulator that I just installed 2 days ago and also the 2 rear coils on the passenger side and still no change. What the heck? ECM maybe? I am scared to take it to the shop, but I do have an appointment on Thursday. Why am I affraid? I have read so many posts on similar problems and people have $1,000.00 to $2,000.00 wrapped up in garage fees and still no cure. Any other suggestions would be much appreciated. If it comes down to changing component after component I can do that cheaper myself than I can have it done at the shop. Thank you for all suggestions so far. Although we haven't cured the probelm I beleive we have to be getting closer and it is that much less that I have to fork out to the shop. Thanks again. Last Update. I have cleaned the MAF and no change. I unplugged the MAF and the engine sputtered once and then went back to running just like it did before I unplugged it. I then decided to see just how much I could unplug with out it changing anything. I unplugged the MAF and the new fuel pressure regulator that I just installed 2 days ago and also the 2 rear coils on the passenger side and still no change. What the heck? ECM maybe? I am scared to take it to the shop, but I do have an appointment on Thursday. Why am I affraid? I have read so many posts on similar problems and people have $1,000.00 to $2,000.00 wrapped up in garage fees and still no cure. Any other suggestions would be much appreciated. If it comes down to changing component after component I can do that cheaper myself than I can have it done at the shop. Thank you for all suggestions so far. Although we haven't cured the probelm I beleive we have to be getting closer and it is that much less that I have to fork out to the shop. Thanks again.

Thank you emmisionwiz. Any comment on the ECM? Last night I made a 7 mile trip on the interstate and when I exited the truck ran perfect at the stop sign and again at the stop light about 1/4 mile up the road and again in the parking lot at Lowes, perfect idle just like new. When I came out and started it, it started hard and idled like **** again. I tried to emulate the drive back home at 55 to 60 and it still ran like **** at idle. I'm confused and frustrated, but I am not willing to give up on her. Anything else you can think of that I might try. I have 2 more days off of work so I have time on my hands. Thanks again for all your help. Thank you emmisionwiz. Any comment on the ECM? Last night I made a 7 mile trip on the interstate and when I exited the truck ran perfect at the stop sign and again at the stop light about 1/4 mile up the road and again in the parking lot at Lowes, perfect idle just like new. When I came out and started it, it started hard and idled like **** again. I tried to emulate the drive back home at 55 to 60 and it still ran like **** at idle. I'm confused and frustrated, but I am not willing to give up on her. Anything else you can think of that I might try. I have 2 more days off of work so I have time on my hands. Thanks again for all your help.