A typical tune up consists of plugs, wires, cap, & rotor. Many people have had problems with aftermarket caps/rotors. Also, AC Delco or NGK double platinum or premium iridium plugs work best in these engines.

If you're going to do it, I suggest going all the way.

 

took it to a chevy dealer today and they pulled the #3 plug and it had carbon build up on it. Didnt fix the problem. They ran a fuel pressure test and it will not hold stead on fuel pressure as it just drops to nothing. They said that the fuel injector replaced and regulator needs to be replaced too. NOT CHEAP!

 

maf sensor in on the intake right after the filter.
you shuid replace all of the plugs. but just one will not hert it

 

Those aren't terribly hard jobs, just take some time. Did they tell you what psi your engine was running at? And did they also do a leakdown test? How many miles are on your truck? If it were me I would replace the fuel filter first. I work my way up from easiest to hardest lol.

And yes the maf is right after the air filter, before your throttle body. Pick up some maf spray cleaner. Its easy to remove and clean, just don't touch the wires! Only use the spray.

 

The fuel pressure would jump up to between 45 and 60 but would continue to drop right after it was engaged by the computer.

They didnt run a leak test.

the truck has 88,000 miles on it.