2000 Chevrolet Blazer

Engine Performance problem
2000 Chevy Blazer 6 cyl Four Wheel Drive Automatic 160000 miles

had intake gasket fixed, and now the ses light is on, and there is a misfire code (ps301) for spark plug one, I have replaced plugs and wires, rotar button, and the distrubutor cap, still gives a code for a misfire in spark plug one, so I also have had injectors cleaned twice, checked vaccum hose, check every pressure line possiable, I also had a alternator installed with the intake gasket, the ses light comes on when you start it and then starts flashing as you accelerate( with a slight decrease in power), it will run rough until you hit 35mph or up, then it smooths out a little more, so I have been told it could be a weak battery, mass air flow sensor, head gasket, or even the intake gasket again, because I have statred to smell anti-freeze when the heater comes on, which I had to flush the heater coil when I got it back to get it working again, does anyone have a solid answer on what is wrong, and how to fix it
February 20, 2009.

Need to do a compression check
check injector if pulsing
weak battery will not give you a one cylinder misfire
MAF sensor will not misfire on one cylinder

Feb 20, 2009.
I had compression tested, told it was good, along with fuel line, and I have no noticable fluids leaking anywhere, where and what is a engine control module coil driver, injector poppet valves, or pcm. Some possible solution's found searching postings on this site, I have also wondered about if it has maybe jumped time somehow, with the code you would assume the problem is electrical from the plugs back, but I have replaced everything in that direction I know, so if there are no sensors you know of to check, would it be more of a mechanical problem in the engine or what

Feb 20, 2009.
Pcm &engine control module are the same
its the vehicle computer ,center command ,the brain ......
if dealing with one cylinder misfire code P0301
PCM is getting no power reading out of the cylinder
in return will turn on check engine light on
you had a compression done and its good
checked and clean the injector and they good
you need to verify that spark is on that cylinder and strong
remove the wiring harness injector plug and verify the all injector pins OK and none was bent or broke

Feb 21, 2009.