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I have been going round and round on this truck with no final fix. I have a 1997 Chevy 1500 5.7 V8, 4L80E. For the past 8 months now it has been running poorly. It will not idle right when in drive, but in park it is better. It will loose power when at speed and when accelerating. It has had cylinder 7 misfire, random misfire, rich, and 02 sensor codes.

I have replaced all spark plugs (AC Delco), spark plug wires (summit), distributor cap & rotor (AC Delco), coil, driver side 02 sensor, fuel filter, fuel pump 1 year ago, and coolant temperature sensor. About 3 months ago I did a Blackbear tune and with that had my EGR valve tuned out (EGR valve and hosing all removed with header install). One day it will be perfectly fine, the next day it will run terrible. After I did the O2 sensors and coolant temperature sensor (did both at same time) it ran better, but still has a slight hesitation / bog. I just took it on an 8 hour trip and it ran fine until the last hour of the trip it bogged and did not want to accelerate.

I have had suggestions of TPS, knock sensor, fuel pump, only use GM wires (I tried AC Delco but they did not affect it so I returned them), fuel pressure regulator, EGR valve (I don't have one), etc. I am getting tired of spending money to no avail, so anyone else expereince and fix this problem before.
 

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My dad recently bought a 1998 GMC K1500 with a new gm crate motor in it..with the same problem...it was throwing O2 sensor codes and random misfire...did all the same stuff your did..and finally after replacing all O2 sensors and new magnaflow cats and new TPS had it retuned he hasnt had a problem since..or if he has he hasnt told me lol
 
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