Used a buddy's snap on smart scanner no codes low fuel pressure not enough to trip the code so I'm going to check fuel pump if not I can only guess it's the spider in the intake

 

ouch 3 ft of water>? did you have a snorkel?

 

Nope thats why my blazer is dead...

 

ouch sucks thats why your parting it out i guess .
looking for a new rig now?

 

Good, you found a scanner. Use the scanner to read the output values of your sensors, get a Haynes manual or research here and verify your sensors are doing what they should be doing. Your sensors feed your ECM data to tell it what to do, if that data is skewed, so will engine performance.

The TPS at idle should be reading 1.2-1.6 volts and increase through the throttle range up to 4.5-5.0 you can check it with KOEO; MAP should be 1.2 to 1.6 at idle and should increase with throttle (check with engine on). Read the O2 sensors (3 of them), they should be fluctuating radically between rich and lean, volts should be fluctuating between 0.1 and 0.9 and should get in that range within first couple minutes (all 3) you should see a constant value change. Also check that the engine switches from "open" to "closed" loop within the first couple minutes of running. Watch your temp gauge, does it match the scanner?

I understand you have not SES light/no codes, but a scan tool will help you find the problem... if used to it's potential. Get the scanner again and review the operational data while the engine is running. Write it down and check this site for what the sensors should be reading. Good luck!

 

My advice would to check for a clogged catalytic converter, that could be a cause for the ups and down on the idle and loss of power. On the 4wd try the fuse, mine did that and it was a blown fuse, look for it as ATC on the fuse box. Hope this helps. Jorge

 

No codes and like I said before the only thing I even see is lowish fuel pressure but not low enough to throw a code