I had a Cadillac I was working on for my neighbor. It did about the same thing after the trans was repaired. Turns out the trans shop cut all the grounds and the ecm was going wild !
I reconnected the grounds after clearing the codes and it ran great.
Semper Fi Marine !
As a former GM mechanic and dirt track racer, I'd jump the compression to 10.8 and run 91 or 93 octane if you can get it. Also total seal rings or child's and albert if you can find them.
I had cylinder leak down at 1% after rebuilds and the oil looked like new for a long...
It also has phosphorus and manganese that others oils took out to save money. We need these for flat tapped cams and lifters. I buy wally mart brand for cheap price and good quality in my work truck with 350 k on it.
Waiting for warm weather to swap it out but use it every day Now.
I installed a 40 gallon tank from my suburban into my shorter k-1500. I reused the straps and added long 3/8 bolts to hold it up. I did cut a new new gas door into the fender and originally took out the fuel pump and used a transfer pump to use the gas gauge in the front tank. After a small fire...
The early Z-28. LT1 350 370 horse used the Holley 3310 which was 780 cfm
I've been building drag cars and Sprint cars since the 60s and used about every fuel system possible. Recently two builds with my children , we put a 406 out of my sprinter into a 90 firebird. Compression at 10.8 total seal...