Not sure if this is where I want to post this, but can anyone tell me where the Engine Control Module/Powertrain Control Module is located on a 90 E250 Econoline Club Wagon 5.8L XL? Any info is greatly appreciated.

 

"Usually" it is located behind the drivers side lower kick panel. You might be able to see the big connector in the engine compartment bolted to the firewall where the kick panel would be on the other side. Double check the passenger side in case I am wrong.
If you have soldering skills, more than likely there are three electrolytic capacitors on the board that bulge out and leak. If you find that, replacing those likely would solve any problem with your ECM.

 

If you didn't find it yet , it is located on the passenger side, either above or below the heater blower motor..
If you plan on removing it you will need a 10mm socket. If you remove the battery it is much easier to get to the plug and remove the bolt that holds it to the ECM.
The ECM comes out from the inside.

 

I have located the PCM! Thanks to all who contributed in my success!