V6 LS that has CEL and RPL come on and then after restarting everything is fine for awhile. This has been going on since I got it about a month ago, I am the second owner. It seems to be electrical, or a wiring problem, but how do you check those things?

you have one or more wires broken inside of your engine harness
the hell of it is that its next to inpossible to find because the wires break inside of the insulation without the insulation breaking
cheapest way to fix it without disecting the harness is just simply replace the harness