Ok I am going to confess about my truck purchase last year. I bought a 1999 C1500 Ext. cab with a 350. It is a nice truck or was until last week. While we were trying to tow our very light Trailmanor RV I got a "SERVICE ENGINE SOON" light. If we tried to maintain any speed going up hills on the interstate, the engine would start to cut out. I had already yanked the cats, installed new plugs and wires (Champion and Duraspark), and replaced the cap and rotor on the road. It runs great if its not towing, and tows at 70 MPH at @ 16 MPG on flat roads. What might be my next thing to change. I'm thinking fuel filter as it is cheap and probably neccessay.

Also the Chevy forums out there really stink. I know I should have bought a Ford, but now wish I had just to get good answers from the FTE crowd.

 

Pull the codes. It sounds like its something simple. My Ford has had the check engine light on more than any truck I've ever owned. It isn't just the other brands hat give problems.

 

I had a Dodge truck act just like yours. It was the O2sensers. When my F150 was doing the same thing it was a coil on plug that was bad. You need to have it scanned at Autozone & find out what is the problem. Don't buy any parts just post your codes on the site. I have a book with all the OBDII codes in it. It sounds like its a simple fix. What Chevy forums are you checking. Chevy Truck World might get you some answers but you will need the trouble codes for anyone to give you good info.
Don't feel bad about your truck giving a small problem like this one. If I was going to nickname my F150 I'd call it Check Engine. That stinking light has been on so many times I've lost count.

 

Autozone's scanner is telling me that it has "MULTIPLE CYLINDER MISFIRE". The 1st time the guy said I needed plugs and wires. I bought the regular Champion plugs and Duraspark wires. They seemed to fix the problem until I was towing uphill and trying to maintain 70 MPH. I Cape Girardieu, MO the Autozone I found told me the same thing. They (and I) aren't sure why I'm still having problems. The wires have a lifetime guarentee, so I might have them check those.

 

You may need a coil , cap & rotor. You may need to get it scanned by a dealer to get a deeper scan done. The scanners used by Autozone don't go very deep into the programming. I've never had much luck with autozone wiring parts.

 

I failed to mention this before. When I torqued the rear screw down I heard a slight "click". I wonder if I cracked the new cap.

 

You may have cracked it. With the high voltage of the new ignition systems it doesn't take much to cause a misfire. I haven't looked at the newer Chevys but I bet their distributors are hard to reach. My 318 Dodge was tough to get to to change the cap & rotor. I'd check the cap to make sure it wasn't cracked. If you can't find a problem you may have to get it scanned by someone with better scanner. Autozones doesn't tell you much. I've run into that problem before. I had to have a Ford dealers scanner put on my truck & drive it to pinpoint my problem.