Okay so long story short, parts replaced and known good Fuel pump, fuel filter, FPR, Coil tested good using multimeter all plug wires had spark using spare plug and grounding method, cap and rotor cleaned, only code popping up is for the MAP sensor its a 1999 blazer.

Background on how it came to be this way driving down the highway vehicle just cutoff all electronics still working eg. lights radio and so forth. not overheating no valves hitting pistons anything like that engine was turning till the vehicle slowed below about 30.

I have read the sticky and dont have all the tools to do the tests but have used alternate methods to get the same results.

Im stumped and could use some fresh ideas, Im greatful for any help you can provide thanks

P.S. the gas down the intake was done with the fuel pump relay removed so the engine was not flooded

 

What did the spark look like? Was it yellowish or blue ?

 

it was yellowish

 

Cap and rotor! if you used aluminum ones throw em out and get delphi/delco.

 

Ill give it a try later today they both are relatively new but know that dosent mean much but their is no fouling on the terminals of either the cap or rotor

 

Had this same issue before and it was the cap and rotor. I had spark just not enough spark.

 

How did it turn out? I have the same issue of truck dying on highway so any help would be grateful.

 

turned out to be the rotor, but replaced both cap and rotor and still has a miss, right now its in the garage replacing both wheel wells and some patch panels but work load has been high so havent had much time for it