I own a 2001 with a auto tranny. It has 110k. Upon full acceleration between 2600 and 3000 rpm it stumbles and &quot;farts&quot; I have drained the fuel and added fuel conditioner<br>but with no results...in fact it is getting worse. is there anything I shuold do before taking it to a specialist? I have had no codes show up.

 

Check the fuel pressure at the VP44 inlet. Could be your lift pump going south.

 

Thats pretty high RPM. Starts defueling around 2700rpm's I believe but shouldn't stumble like you are describing. But, yes, check FP for sure before doing anything else. Don't let the dealer do it. Network with somebody that has one of those Briar Hopper style gauges. That way you can check it in the real world under WOT. Also, a valve adjustment might just be in order. You also don't say when the last time was that you changed the fuel and air filter.