well as we all see the 4.3 has problems. well a few months back i water lock motor in a flood. did everything safe by pulling plugs and drain oil gave it a week to dry out before i tryied to start. well everthing went good truck started fine.
so i did a complete tune up,cap,rotor,wire and ac delco rapid fire,fuel filter, air filter, clean throttle body(took off). also had to replace tps and iac(twice).(i work in small auto repair shop) used modis from snap on to diaganose my problem.
ok now my problem is code po 300. check for vaccum leaks, check fuel pressure,check injector balance. so i again replace cap rotor wires plugs again still problem. now last wednesday the truck spuddered bad big loss of power. the the day the truck ran great had no problems no miss ran like new.the next time i got in to drive it went back to running bad and missing. i have done seafoam in the gas and oil.

i hope this info helps and ideas or suggestions would be great.
thank you

 

did you check your tranny fluid?

got water in your cat, exhaust system?

 

Levi, don't forget to clean out your EGR valveand PCV.
How deep was the water level on your Blazer? Do you think it entered the intake area?(hydro lock/connect rod issues)