slima, thanks for your suggestion however I tried that already along with other grounding points and it didnt make a difference. I also had our radio guys over trying to help figure it out. I also have four trucks in my fleet and this was the only one that we had the problem with.

 

first military radios are FCC compliant. Mostly THANKS for the final out come one of our 6.0l ambulances had the same issue and same repair the shop used non OEM ICP the OEM one made it run good again! again Thanks.
Ours would stall at low rpms but over 750/800 it would speed up 500 rpm every time you keyed the radio. showing no codes and even the cruise control wouldn't slow it back down, set it @ 60 key the radio and the ambulance would speed up and stay at the new speed until un keyed it. The scanner didn't even show the rpm change but the dash tach did and you could sure hear it. The ICP was the only part changed (due to codes) and started this issue.
You could cause this with a handheld in the cab (Motorola and king) the dash mount Motorola 2013 compliant, even a mobile King or Motorola in a different vehicle if within 20 feet or so. Don't care what ford says it will do it. our shop folks put our old ICP back works good a new ford ICP works good 2 new NAPA ICPs and same problem.

 

Did you use a motorcraft icp
The wires shouldn't matter but the part would i went threw 6 standard crank sensors on a no start condition then finally got a ford one and like magic she fired up

 

As a matter of fact that is what I ended up using. The after market ICP's were being inturpted by the radio frequency.

 

Searching for the RF interference on the 6.oh no! Found your forum. I concur since fixing the oil leaking out the piggy tail of the ICP, the after market sensor interrupts the engines tuning when PTT is keyed on VHF radio. Jagged little pill for a weeping set of ICP wires. ICP Training = about $500.00.