Got a new problem. Kinda out of the blue, it feels and acts as though I'm trying to go up a very steep hill when I accelerate. It down shifts way too early and when it does there just isn't any power. Its a little more resistant to starting up than usual but not really a problem -- just a few more revolutions before its running. It idles smooth and as I normally drive it like a geezer wearing a hat in a Buick, it doesn't act like there is anything wrong driving it through town. But anything over 30mph and it becomes apparent that there is a problem. I'll get a cylinder misfire code and a service light if I accelerate to 50mph and I'll get a blinking service light if I put my foot into it. I can get it to 65mph if I take it easy and it'll maintain 65 on cruise control but there is a clear tendency to downshift inappropriately trying to get up to speed. All the time, it continues to be a smooth running engine with no surging or shuddering.

My first thought is bad gas and that is followed by fuel delivery issue. There's at least 12 gallons in the tank and if things don't get any worse, I'll run it to near empty and fill it back up with premium and some additive. I'm going to see if my local autoparts can rent me a fuel pressure gauge. I'll do a compression test if the fuel pressure is good. It sucks that the fuel filter is in the tank.

 

The lack of power, and misfires would make me wonder if the cat wasn't getting plugged up..... Try physically removing the front O2 sensor from the cat. Go for a drive. It'll be louder, but, see if it runs any better.

 

Put a full dose of Risolene fuel system cleaner in yesterday and today it seems to be slightly better. Maintained 65 on the interstate without downshifting on any upgrades. It still isn’t right. Drives exactly like I’m pulling a 2000lb trailer. I’m gonna burn the rest of the quarter tank of gas and put in a half-tank of new gas from a different source with another dose of fuel system cleaner.

 

Update
The Risolene fuel treatment and burning the remaining gas left in the tank seemed to have cured the problem. I ran the truck to dangerous empty and refilled it from a different gas station. It could either have been bad gas from the pump or I have a failing gas filter that was partially cleared by the fuel treatment solvents. If the problem returns, I'll drop the tank and replace both the pump and the filter. I was getting both specific cylinder misfire codes and the random misfire code and they've stayed cleared for almost a week. I had something quite similar happen to my Harley a few years ago -- just crappy gas that led me on a wallet draining goose chase.