I have a 98 3.9L DAK that has started bogging down from a stop. Doesn't happen all the time, and strangely enough, seems to happen more while doing a left turn. The tach doesn't show revving. Lasts a few seconds, then engine kicks in. Noticed a bit of power loss, but the engine has 125,000 on it. Had a P0135 code, indicating oxygen sensor problem. Haven't tested them yet. Starts ok and idles fairly smoothly. Has new plugs and air filter. Wires tested within specs. Ran injector cleaner through. Any ideas about what could be causing this? The intermittent nature doesn't act like a usual fuel flow or ignition problem. Thought of maybe a transmission issue, but the bogging only happens coming off a stop. Other shifts are just "normal" DAK behavior. Odd because I don't hear engine revving going into or out of the bog. Just comes back up like nothing happened.

 

Sounds like an o2 sensor to me. I'd start there especially if you have had an error code for it.

 

it is strange that you only notice it on a left turn, but it would just be a coincidence...anyway, you might also want to check your fuel filter, as a bad one will cause the engin to start bogging down, especially when you really get on it. try getting on it kinda hard once, and if its bad enough, the truck might just stall out all together. it very well may be the o2 sensor as well