Mine did the same thing throwing a p0300. It was the upstream 02 sensors going bad. I replaced both upstream sensors and it hasn't run bad or threw a code since.

 

Any chance 0300 could be due to a bad cam shaft position sensor... or at least one that is failing?

 

Here is what I found on the P0300 code:

A code P0300 may mean that one or more of the following has happened:
•Faulty spark plugs or wires
•Faulty coil (pack)
•Faulty oxygen sensor(s)
•Faulty fuel injector(s)
•Burned exhaust valve
•Faulty catalytic converter(s)
•Stuck/blocked EGR valve / passages
•Faulty camshaft position sensor
•Defective computer

Possible Solutions

If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

 

The thing that confuses me is that I can disconnect the battery to reset the ecu and the truck will run fine for 2 or 3 days then throw the p0300 code agian and start running bad. If it was an o2 senser or something like that wouldn't it run bad all the time instead of clearing up when I reset the ecu by disconnectig the battery?

 

02

Well, my truck would run fine for a month at a time then suddenly start to misfire. Sometimes it would clear up in a couple of minutes sometimes it would be hours later. After changing my upstream sensors it has had no issues since. It was explained to me that a sensor was starting to fail internally, and would be ok sometimes but send bad signals to the ECU randomly. If your sensors are getting old it may be worth a shot to change them and see if it fixes the problem.:smileup:

 

I am currently having the same issue. After startup and driving for a few seconds all of a sudden the engine hesitates and almost dies as if almost all but 3-4 cylinders die. No clue what the problem is I’ve already replaced all spark plugs and a few coil packs as they had gone bad already but after it sputters for a few seconds it goes back to normal and doesn’t do it again till the next start up. Any ideas?

 

I am having a similar problem p300 with a 131 and 132 code just changed the plugs not to long ago ran fine for a moth or so changed the up stream o2 sensor and pulled the battery ran fine for a little bit then came back. Also replaced coil pack 1 and 3 got 160,000 miles on it any thoughts would be appreciated.