My latest code is p0300 on my "98" 3800 drives fine but sometimes boggles down and seems to accelerate little to nothing. It all started when cat almost caught fire (glowing red, smoke and could smell melting plastic) while in highway traffic. No good auto repair man replaced ICM and the random engine boggling began forgot what he did next but never went back. Since then replaced plugs and wires got a code replaced cat then another code replaced downstream o2 sensor got another code p0405 egr and during that a code for #6 cyl misfire showed once, cleaned egr and reinstalled with new gasket SES light turned off but now another code p0300 random misfire and SES light not on yet
NOT READY TO GET RID OF IT YET still fun to drive it has close to 200k 5speed manual with a possi rear end but the engine boggles down at rondom times.
ANY IDEAS TO FOR P0300!!

 

Here's what one website says about the P0300.

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

Try checking. Your fuel pressure. Chances are you have leaking or clogged injectors. Also pull your number six plug. See if its all fouled out or if it's white from being to lean.

 

I've had a PO300 a couple times before, and both times it was a clogged injector. A few of those things on the list above (oxy sensor, cat, EGR, cam sensor, ECM) will or should trip their own code. So if you're not getting those specific errors, I'd check out the other ones that are left.