Good Afternoon,
I currently have the P0300 code on my 2001 chevy blazer. It seems to idle normal, but when accelerating it likes to chug and sputter. This problem is not noticable one up to speed and warmed up. With in the last year i have had the spark plugs, wires, distributor, fuel pump, and fuel filter changed. I took my blazer to Firestone to do the sparkplugs due to a broken and arm and have noticed that they install Bosch plugs. Is it possible that these plugs are what is causing the code and missfire?

 

There are many things that can cause a P0300 misfire code. The circumstances under which the code is appearing should be stored in the PCM as freeze frame data. It is possible that a sensor is going a bit out of range causing the behavior. A dirty MAF sensor can do this.

The quality of the components you replaced can have an effect as well. Aftermarket caps & rotors for instance; on these engines, they do not seem to hold up well and often fail right out of the box. The general consensus is that AC Delco caps, rotors, & plugs work best in these engines with the least number of defects.

The same goes for the fuel pump. What was the reason it was replaced? What brand of pump was used? Do you have the means to monitor your fuel pressure while cruising down the road & experiencing the misfire?

 

Have you checked the fuel pressure?