[Oldtruckfanatic]

As the above said if you arent comfortable looking up the test procedure for diagnosing the sensors etc. Try giving a reputable shop a call. You can do a search of those codes and get the diagnosric procedures. Its best to do that before just throwing money at it and when you do have no doubt you will find several forum threads on getting bad non gm sensors. Lots of guys have used aftermarket sensors with success i just personally chased a problem on a 53 chevy with a 5.3 for about a week and after we switched to gm sensors and harnesses the engine light never came back on. I still diagnose before I go replacing soneones new parts and charging them I was just giving you suggestions on where to start looking. Yes the knock sensors causing the pcm to default to a base timing setting will cause poor mileage and drivability concerns. But so will a bunch of other things so dont just replace parts because aftermarket knock sensors have been a problem before. It can get costly to just throw parts at it and find out there was another issue. I just gave you information I have experience with as a place to start looking. Hope you get it figured out. Sucks to pull that intake off after having it off to avoid this issue in the first place.