I have a 2001 Blazer it throws the random cylinder misfire code. I have replaced the cap, rotor, plugs, wires with msd, new coil, deleted cats, new O2 sensors, new distributor, new crank sensor, new crank, new spider injection. When truck is idling runs like crap and check engine is flashing. It loses oil pressure when idling will not get over 30 P.S.I. at wide open throttle. I thought it was the cam berrings so i took the engine out took it apart sent it to my local machine shop to have them installed he said there wasnt anything wrong with the old ones. But replaced them like i wished. COMPLETE OVERHAUL DONE because of the oil pressure but it still does it.

Any ideas please help love the truck been a mechanic for 18 years and have never came across something like this

 

No leaks, squirts or seeps? As a mechanic of over 25 years experience the one thing I do know is you will always run into something you don't know (especially on your own vehicle). Schooled technicians (still a mechanic) are taught a logical process of trouble shooting and what is likely; what they don't do is teach you how to think outside the box.

My S-10 was not starting whenever it rained and the airbag light came on around the same time. I figured they had to be linked somehow and frantically searched for a bad ground or something. My wife told me to change the distributor cap (she really doesn't know vehicles, but she was right). She was never taught how to think inside the box so everything she thought was outside it's confines.

She would say change the oil pressure sensor.

 

It does not have any leaks tings or anything and it didnt when i rebuilt the engine. it runs like a scalded dog at wide open throttle but idling it sucks and the low oil pressure comes on but thats proble because of how bad it is idling

 

Perhaps the oil pump? I didn't see it in your list of parts replaced; though, I am sure you have already tried it.

 

Yes I thought it was the oil pump to start with also, so I changed it before I rebuilt the motor and then when I rebuilt it I replaced it again just to make sure there wasnt something wrong with it. And i have also had the cam
Bearings changed in it also.

 

The only thing i can think of is a bad sensor is giving the computer false readings and is causing it to try and compensate which makes it run like crap; much like the lean/rich running problems.

 

You wouldnt have any idea of which sensor it could be would you. I was looking up some other things on the internet awhile ago but nothing says anything about the oil pressure and running like crap its one of the other. I was thinking it might have something to do with the ECM

 

Without an in depth scan with the proper diagnostic equipment, it is a shot in the dark, but I would start with the oil pressure sensor. Sometimes the most direct route pays off, and is the only one that makes sense right out of the gate.