Every 4days reduced engine power light&sts alarm is coming on dash board

have it scanned....If codes indicate any kind of idle, throttle, misfire or even Evap codes. 8 of 10 with these issue need to peel it all back to the throttle body, then remove, and finally when finished, repeat all steps in reverse order. pull fuse numbers, 28 and I want to say 10 for the 2 pcm fuses. After 15 mins replace these fuses and continue with relearn sequence until its determined if this is the kind of fix you need. There should be an active recall of all vortec 4.2L engines But that would entail GM admitting they were schematically inept. the other 20% of the time its all hit or miss, with various sensors, short outs, etc.