Surges and loss of power when hot.

[Mlabastide]

Alright y'all... This is my first time turning to a forum for help.

First off, here is the vehicle details.
1986 Ford Bronco II
2.9l
Manual Transmission
4x4

Issue-
Runs fine before the engine gets to operating temperature. Once at temp, the truck will start to surge. To clear it out, I can clutch in and give it a quick rev. It comes back within minutes.

I also noticed a clicking sound when I turn off the engine over on the pass side fender on the EGR?

Things I've done so far.
Replaced
Ignition control module
MAP sensor
Engine coolant temp sensor

My next stop i think is replacing the O2 sensor?

I am a aerial equipment technician, I do not work on vehicles. I do know the basics and know how to use diag tools. So any advice would be greatly appreciated.

Should I replace the O2 and go from there?
If not, where else should I start.
I did everything that I found on forums, and also did the coolant temp sensor because it seems to be running too rich. Thinking maybe the computer thinks it is still cold. ( Had no reading on temp gauge. I replace both the computer and temp gauge sensors)

PLEASE HELP
Thank you,
Mitch

 

[Cees Klumper]

I am not sure whether your year truck has the OBD I diagnostic capability (my '90 does) - if it does, I would get or borrow at AutoZone or what have you, a code reader. The instructions are a bit complex, but if you follow them to the T you will get codes and this will point you in the direction. For example, on my truck, I did get a code 'O2 sensor values out of range' and so I installed a new one and the code went away, and the truck runs fine again.
Other thoughts would be to check the fuel pressure (assuming you have fuel injection not carburetor - I really don't know much about this truck), the ignition timing, other ignition components, and check for vacuum line issues/leaks.
I am sure others with more knowledge will chime in soon. Good luck with the diagnosis/fix.