Hey there,

My girlfriend was driving down the road today in her 2004 Acura TL and it just wouldn't go over 55, it would not Rev.

Car just had the timing belt replaced 2 weeks ago, and is at 106K. I am thinking this might be an APP issue?

What do you guys think.

 

sounds like the car went into limp mode and could possibly be the APP sensor.
Did it throw a CEL?
if so, have the codes read from an auto parts store.

 

Hmmm....I think limp mode limits you to well lower than 55, more like 20-30. Usually an APP sensor fault will throw a code.

Is it an AT or MT?

Take the car to any auto parts store and have them check for codes (DTCs). It's free.