Code PO300 random misfires
 

Having issues, especially driving up hills. First thing I did, changed upstream O2 sensor (was giving a code for that too), and replaced plugs w/Delco Iridiums. Didn't seem to help much, though less CEL. Changed the plug wires last weekend, wasn't sure of any improvement. But after a week, I'd say some improvement at least, but still getting this code. What to look at next?

Check fuel pressure.....pump may be on it's way out.

Yup. Fuel pressure is next on the list.

I haven't had a chance to change the fuel filter, so there's a possibility...

misfire with load in overdrive, check coils.

This thread was over 38 months old when a new post was added. Moved that post to https://www.gmforum.com/pontiac-168/...isfires-312890 and closed this thread.