Hey guys, long time lurker here finally joined. I wasn't able to find a solution to my issue with the search button so I figured I would would start my own thread.
My truck has been running fine for over a year now, but now it's having an unknown issue. Basically it idles fine, but as soon as I put it in gear it starts acting up. There is a loss of power, and right around 2k the whole truck starts to rock back and forth. If I really punch I can kind of "power through" and get it into 3rd, but same thing with this gear. As soon as I get the revs up it feels like the fuel is cutting in or out or something, and the whole thing starts rocking. It does it in 4th, and 5th. It's been getting worse and worse and I have to get to work so I need some suggestions. At first I thought it was a fuel pump/filter issue, but it revs just fine when not in gear. Then I thought it might be a misfire, but again, when it's not in gear the truck looks/sounds like normal. At this point I'm open to any suggestions.

 

same symptoms in nueral?
These trucks do not have fuel filters, but easiest way to tell is put a fuel pressure gauge on the fuel manifold. I would pull a plug and check the condition/gap/type.

 

Nah, whenever I take it out of gear it idles fine. Stays at a solid 600 or so. Needle doesn't jump, and the truck doesn't appear to idle rougher then it ever has. Yeah on the way home from work I plan on picking up a set of plugs and wires just because the truck is due for a tune-up anyway.

 

Check Engine light has been on since before the issue, but it doesn't blink or anything when I'm driving around. Since this is my work truck I really need to get this going. I'd rather not pay some idiot to jerk me around unless I have to.

 

Disconnect, and remove the front O2 sensor. Take it for a drive. See what happens.

 

Alright I'll do that when I get home.
I take it if it works fine then the sensor is faulty? Either way I'll post the results.

 

No, that means the cat is clogged and the plenum gasket is shot. Read the plenum sticky.

 

If the cat was clogged wouldn't my check engine light be flashing?

 

Alright my bad, I saw the plenum sticky, and chose (mistakenly) to ignore it.
That pretty much sums up my issue.

 

The cat is just not totally clogged yet, thats why no flashing CEL.