I finally found the EST Bypass connector and set the truck to the correct timing, it does not bogg down as bad as before but not I have spark knock bad. I live at the beach and have always run 87 octane I did a complete tune up last week but still no good results. ANY IDEAS????

something in the cylinders? how old is the truck??

I believe the clys are clean the truck is a 92 4.3 tbi. i have tried everything i can think of, but now i get the spark knock