so my sister has a 98 s10 blazer 4x4 thats having some severe problems, the truck will idle perfect no shaking nothing but it will not rev past 2000-2500rpm, I figured fuel problem but the injector/regulator and spider has all been replaced as well as the pick up sock on the fuel pump (it was completely clogged up) it seems the truck has had the head gaskets replaced as someone slopped gasket maker all over the front of the engine. also it builds pressure in the radiator within a few seconds of the truck being started. I figured a blown head gasket but there is no coolant in the oil and the coolant level is NEVER low, the EGR has also been replaced and it has very good fuel pressure holds it when not running and doesnt drop off when it is running, I am at a loss here so anyone have any ideas? oh and the only code it throws is p0300 random misfire

 

The cat could be clogged up.

 

I have seen this kind of thing happen on a cat C7 diesel engine but that was because of a sleeve in one of the cylinders had cracked allowing compression past the O rings in the head. since there is no sleeves in the 4.3 I doubt thats it lol,

I guess if no one else can come up with anything I will end up tearing the whole top of the engine down anyway at that point replace head gaskets etc, it doesnt look like who ever did them before had a clue since I am pretty confident there is a whole tube of gasket maker on the front of the engine alone. I do on the other hand have to get this figured out ASAP because i have a TPI V8 waiting for my blazer and the 98 is in the way!

 

well it seems we got it figured out, seems it was a combination of the cat and the fuel pump, after replacing the fuel pump the vehicle would rev to about 4300rpm but thats still not right so we drilled 2 large holes in the cat and it runs great... now it sounds like an air compressor venting lol so a new exhaust is coming hopefully this week