My 96 k1500 5.7 is throwing the famous PO300 and PO161 code. The only thing is the truck runs smooth as glass with no power loss. The only noticeable loss is the 2 mpg drop. I was getting around 15mpg, now it's only around 12. I replaced the intake gaskets a couple of months ago, so I know that's not the problem. It has a new distributor, wires and plugs. Also the SES light goes off and on occasionally. I've heard of people having these codes with driveability problems (rough idle, hesitation), but that's not the case here. Any suggestions? Thanks!