Hey I have an '03 F-250 superduty V8 automatic with a 5.4 gas engine and 154,xxx miles on her. Recently I have been experiencing problems with her. Such as stalling while in gear, she mostly does it if I am driving at a good speed and have to come to a quick stop, but also does it if I switch from park to drive or park to reverse or drive to reverse or vice versa. While idling in neutral or park she seems to be fine. Also if i switch gears and get right on the throttle she is fine.
Also my RPM's seem to be screwing up. Up until 45MPH she will shift and the RPM's will go up as needed, but once I hit 45MPH the RPM's fall right to 1500 and stay their at a steady rate even if I really hammer the throttle.
So far I have done an oil change (just because it needed it not thinking it would change anything) and cleaned the IACV hoping it would help with the stalling but it has not changed anything. Also just want to make sure I have talked to a couple people and they say it shouldnt be a transmission problem but just want to double check. Just looking for some helpful pointers I could do myself with tools in my garage before sending it to my mechanic and get charged $80 per hour...thanks for any tips or pointers

 

First thing I will do is give you a bump, second if I remember right the tach reads off of the crank sensor so if the PCM is getting a bogus signal from it that could cause all the symptoms you describe. Hopefully someone that knows for sure will chime in..