06 V8 trans issue

[t0ked]

My dad has an 06 Explorer V8 with 95k on the odo. It seems the transmission is sticking in gear when there is any load on the engine.

Whenever the AC is turned on or there is any load on the engine, it seems the truck gets stuck in either first or second gear and is slow to shift. This results in sluggish acceleration and a very loud engine until it shifts at around 30mph. I can usually "fix" this by manually shifting it down to 1st gear at a stop and quickly shifting to "D", but only if the load is removed (turn off AC, etc). There are no dash lights or codes being thrown. Other than an extremely sluggish and loud engine, the are no other symptoms.

A trans reprogram and flush was done at around 85k. Spark plugs and coils replaced at around 90k.

Any ideas?

 

[4pullingGM]

Not sure if it is what is going on with yours, but I have seen plugged fuel filters cause that. They run great at an idle, but have no power and the trans won't shift when accelerating, which results in high engine rpm. I found that the fuel pressure was dropping to almost nothing while under load, but was perfectly normal sitting at an idle.

 

[t0ked]

I forgot to mention the fuel filter was changed at 80k also. It also only does this when under load. Majority of the time it runs great. It's guaranteed to do this when I turn on the AC. Sometimes it'll do this randomly but not often when driven normally.

 

[Tech By Trade]

No codes, Plugged Cat?

 

[t0ked]

No codes. Got the code for the cats a few months ago and still does it after new cats and O2 sensors