code po301 and po300

All right guys, I'm working on a 1999 Taco w/ a 2.7 engine... It came to my shop with a misfire and barely running. Scanned the computer and got codes PO301 and PO300. Replaced plugs and wires and reset memory, now I still have the codes and it doesn't run any better. And I do know it's not the coil packs. I don't know which way to go. This truck has 305,000 miles on it also. Any help would be greatly appreciated...

 

The codes are as follows:

P0300 Random/Multiple Cylinder Misfire Detected
P0301 Cylinder 1 Misfire Detected

Not sure if that helps you any, hope you get it all sorted out though.

 

I know the code definitions... Thats why I started with plugs and wires, and checked the coil packs.

 

Got good compression?

 

I haven't checked that yet. I wonder if the valve adjustment could be causing this???