I have an 04 fx4 that at about 2000 to 2500 rpms in 1st, 2nd and sometimes 3rd is very sluggish. It usually only happens when it is warmed up or warm outside. When I first get in and take off for the first time of the day it doesn't do it. After it warms up, it happens more frequently than not. I also get a code P0506-valve duty cycle lower than normal. Any ideas?

 

My booklet for this code says rpm lower than expected. I would go to your local library and see if they have an Emissions and Powertrain Control manual for your vehicle and diagnose that code. If a Ford manual isn't available, see if they have a Motor Emmission and Powertrain Manual for Fords. Motor is the publisher. Motor manuals have been around for decades. I remember seeing them in my uncle's gas station in the 60's. Follow the diagnostic routine in either manual and it will get you the fix.

 

Yeah, it also says the rpm thing, I forgot that. Thank you. I will look into your suggestion.