You can rent the code reader from O'Reillys and other parts stores, most will rent for free, just leave a deposit and you get the deposit back when you return the tool.

Oh, I didnt realize they would rent those out. I bought a bluetooth obd2 adapter for use with my phone. It comes in on wed and hopefully it will work and let me view and clear codes also.

The most common problem that causes limp home mode is spark plug wire, next is the wiring to the coil then the coil itself. Start in that order. good luck.

We should start up a pool. Or take bets.

My money is on the throttle position sensor or TPS wire going to the throttle body.

I know I have a miss on 7 cylinder. I have verified that the plug, wire, coil and coil subharness are all good. I even swapped everyting to 3 cylinder and no change. I put a noid light to the 7 injector plug and it is working properly as well. The only thing I can come up with on this is that either the wire going to the coil from the PCM is bad, or the injector itself is physically clogged. But honeslty would a miss on one of the 8 cylinders cause the transmission to go into "limp mode"??

I can tell you ive had a 5.3 for nine years and when i had a miss i could still fry the tires..03 GMC AUTO

I know, there should be no reason the computer would go into limp mode over a misfire, that just seems excessive. I mean multiple cylinders or one whole bank maybe, but not a single cylinder.

Funny enough I was sitting in on a class today and a similar discussion came up. According to what some of the guys were saying if you open the throttle body on a drive by wire set up manually (we were discussing cleaning and checking TB) you can throw the DBW system out of Wack and cause the car to go into limp mode. Just an FYI...

Ok, so I scanned the PCM and got the following codes;
P0300--Random Misfire(which I know cyl 7 is missing)
P0351--Ignition Coil "A" Primary/Secondary Circuit (which doesn't make sense cause its cyl 7 missing, not cyl 1)
P0740--TCC Circuit
P0753--Shift Solenoid "A" Electrical
P0758--Shift Solenoid "B" Electrical

So Im thinking the reason Im getting all 3 of the transmission related codes at once is because there is an issue with the wiring or connector going to it. It just seems unlikely that all 3 of these things would go wrong with the trans at the same time. Am I wrong for thinking that?? Any Ideas?

I would go back and double check the wiring / routing for all of the circuits that the codes (0351-0740-0753-0758) are pointing to. Where did the harness come from for the conversion?