I have just recently purchased a 1999 F-150 XLT 5.4L It just recently started having issues... When it is wet outside and the engine gets warm the whole truck shuts down. And it's not like anything I have ever seen. The engine is not sputtering out it just shuts down. Now when this happens the THEFT light starts flashing like crazy! And the digital odometer does not display numbers just lines. And will not start back up till the engine has cooled down some. And then I can ease on to the gas and limp back home... But if I go over a bigger bump shuts down again and have to let it cool down again. So I took it to the shop and they could not find anything wrong with it. The only difference is the day they looked at it it was dry and it ran fine! So I am guessing it's just something getting wet that's not supposed to.... What can I check? THANKS! New on here so any help would be greatly appreciated!

 

GEM module getting wet? Maybe I'm thinking of another issue

 

check the wires and connections on the transmission on the drivers side.

 

If you go over a bump and it shuts down it kinda sounds like a loose connection
somewhere.