91 5.0 5spd basically dies every time I'm going downhill on the highway, or if I am slowing down to get on the exit... Luckily it's a manual so I can just pop the clutch and it starts right back up otherwise I would be In trouble. Seems to be ok in town unless I step on it then slow down fast... Does this sound like a crank/cam sensor, or do these trucks even have one?

 

Bueller...Bueller...Bueller

 

i don't believe your truck has one. Check the PIP (stator) in the distributor.Crank Position Sensor - Ford F150 Forum - Community of Ford Truck Fans

 

Replaced stator, still happening... Any other ideas? For whatever reason it's specific to the highway, in town it's fine.

 

Check your base idle setting. Warm up the truck and unplug your IAC, if it dies your base idle is screwed up. You can adjust base idle by bending the tap that touches the base idle stud

 

There is not a base idle on these trucks.
Sounds like the OP has a bad IAC valve.
The idle is totally controlled by the PCM Computer.

 

Look at the throttle linkage on the throttle body. There is a stud that the factory sets for the "base idle" When properly set a warm engine should run with the IAC disconnected. The IAC just compensates for differences in conditions that the motor faces.

 

If you are talking about the screw that stops the throttle plates from closeing that is a factory setting to keep the throttle plates from sticking closed. It is not to be messed with at all.



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That's the one I'm referring to. After my motor swap I had to adjust mine slightly to bring the idle up. It might be there to keep them from sticking closed but I'm under the impression that it is there for a base idle setting as well. The IAC is there to supplement but the throttle plates are the main source of air at idle

 

By the way the engine should die if you unplugged the IAC valve.

 

No offense but what are you basing that on?

 

KE1 DIAGNOSTIC from DTC 412 from the 1995 POWERTRAIN CONTROL/EMISSIONS DIAGNOSIS manual.

 

In my limited experience (15 years with OBS trucks) I have seen these trucks die completely when the IAC is disconnected or idle very low, i.e. 400-500 RPM. Bill has been around these a lot more than I. I would prefer to have the low RPM.....as long as the TPS closed throttle voltage is within range or the throttle sticking.

 

Bill,
Maybe as a factory spec they are supposed to die when IAC is disconnected. But the manual is assuming its a brand new truck with no malfunctions. In an older machine with worn parts and unknown failures whatever they may be I would prefer to have a higher base idle so the margin of error is a little larger. IE so if your IAC is sub par your not putting 100% of the engines ability to idle into the ability of the IAC to regulate airflow. Another example would be my 90 f150 with a 90 5.0HO motor in it. The 90 f150 motor and 90 mustang HO motor are vastly different animals. I'm Running the HO motor off of the stock non HO motor computer so the parameters are different so I had to adjust the base idle.