I hadn't a97 blazer 4.3 vortec that last sunday started running like crap. Its misfiring really bad to were I can't really drive it at higher rpm its smother. I've changed the injectors, wires, crank position sensor, cam position sensor, fuel filter. I can't figure this out its my only car and I ran out of money trying to fix it please help.

 

Wow no wonder your running out of bread. If you have an MAF on that beast unplug it and see if it helps. If so clean it. You should do a fuel leak-down. What made you go right for those sensors and spider, kind of expensive stuff just to start changing.
You know cap and rotor are always a good place to start but these are two things gotta be delco. Sounds snobbish but they yell at you here if you go with anything else and there kind of right.
Did you have the check light on before crappy running? Just wondering what might have come first the o2 code or misfire.

 

I've cleaned the mass today and I bought it with a cylinder 6 misfire was told it was injector the cel had been on since I bought out so I figured another injector went bad. Then I had a crank position code but I think it was my fault I bumped the distributor.

 

Could it be a bad o2? Or is the misfire code most likely the cause of the o2 code?

 

Someone please help idk what to do I have no other vehicle I'm still driving it because I have no choice and I'm afraid I'm gona cause more damage. Someone told me maybe timing chain or cap and rotor truck has 193000 on it

 

First we need to find & fix the problem, then we can go back and take care of the crankshaft position sensor relearn and camshaft retard. Both of those are necessary to do when you replace the crankshaft position sensor and camshaft position sensor, (requires a capable scan tool to perform both operations).

As spittybays mentioned, check fuel pressure and leakdown first. Low fuel pressure can set a P0300. Key ON, engine OFF, fuel pump running: Pressure must be 60psi to 66psi and must remain above 55psi for at least 10 minutes after the pump shuts off.

EDIT: Very doubtful it's the timing chain, not a common problem at all on the 4.3L. Spittybays also mentioned cap & rotor, and that's a real possibility The P0154 is indicating the passenger side oxygen sensor, (same bank as #6 cylinder) is dead. That may be the cause of, or contributing to, the P0300.

 

I tested pressure when it was running it was 55 didn't have time to let it sit I had to rent the tool

 

Better rent the tester again, follow the procedure in post #6. Fuel pressure must be tested with the engine off. If it fails any part of the test, you'll need the tester to pinpoint the problem.

 

OK...running pressures, sorry to to say, are useless in diagnostics. Get the gage again and follow the Capt's directions, also read the fuel system diagnosis in the BF diy.
The first part of the leak down test will take no more then twenty minuets. If it's bad and you have to isolate pump from injector it will take some more time.
If you have zero dollars take the cap & rotor off and clean them with some 120 grit sand paper. When your in there you will see some breather ports. There may be a screen on them there may not. Make sure there clean, they allow the inside of the distributor to dry when theres condensation.

 

I tried to sand the cap and rotor and it fight make a difference I'm can't test the fuel pressure until I get paid again but I have noticed most the time while driving above 2000 rpm must the time it smooths out and when the tricks cold its worse until it warns up a couple mins