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Started with a p0300 code and progressed

(2001 Chevrolet Blazer)
in Defiance, MO on October 25, 2009
i was driving normal highway when my check engine light came on and the performance went away and was running rough, got home put my scanner on it and came up p0300 random misfire, so I knew that the fuel pressure regulator inside the plenum is prone to go bad on the spider pump, so upon inspection and hooking it back up to the fuel and pressureized the system it wasnt leaking but the intake was clean by it and could see where fuel was running into the number 5 intake port. replaced the regulator then cleared the code and started it and it was still there, so then i replaced plugs, cap and rotor and wires were good and new also, te rotor had a wear spot worn thru it so i thought coll it was fixed s i started it and it started right up, then after running for a few minuates it started sputtering and coughing again and i noticed on te scanner that the o2 sensors was reading lean and started smelling a burning so i looked under and the pipe in front of the converter was glowing bright and back by the muffler and when i started it it sounded like it was restricted so after seeing te glowing i went back to the tail pipe to feel if it felt restricted and could not even put a shop towel over my hand to close it off it was that hot! so wat im trying to figure out is, my converter clogged up from it running so rich before and dumping alot of fuel into the converter and its so full that it caused it to clog? i have almost given up with this, and i have worked on cars for a long enough time to figure this out but this ones got me big time, all the sensors and fuel pump is good and i'm thinking more towards now to the exhaust off at the h pipe and see if it runs smooth again!! any ideas or a solution would be great please!
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Popular Answer
on October 25, 2009
Common Problems that Trigger the P0300 code:

* Worn out Spark Plugs, Ignition Wires, Ignition Coil(s), Distributor Cap and Rotor (where applicable)
* Incorrect Ignition Timing
* Vacuum Leak(s)
* Low or Weak Fuel Pressure
* Improperly functioning EGR System
* Defective Mass Air Flow Sensor (MAF)
* Defective Crankshaft and/or Camshaft Sensor
* Defective Throttle Position Sensor
* Mechanical Engine Problems i.e Low Compression, Leaking Head Gasket(s) or Valve Problems

Common Misdiagnosis:
Fuel Injectors
Oxygen Sensor(s)
Power Train/Drive Problems

on July 23, 2010
Try to take out the o2 sensor before the cat(unscrew it). and see if it runs a little better if it does then either hollow the cat or replace it. if you replace it spend the extra dollar and get the high flow cat. But if its your cat thats getting red hot chop it out and replace. that can cause a big fire. i had a caravan do the same thing, actually caught on fire
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