I've been dealing with a rough/surging idle on my 1983 245 DL. What I've done so far:

new plugs, wires, cap, rotor
clean throttle body
new FI temp sensor
clean flame trap
new injector seals
clean idle air control valve

I suspect the idle air control valve. It is of the three wire variety. I applied 12V from center terminal(-) to each of the other two and heard a click one way but not the other. After doing that I adjusted the base idle with the knob under the throttle body and when I reconnected the IACV the idle did pick up. I'm still not convinced that this is not my problem.

I did a resistance test as per Bentley and was in the neighborhood of what it should be but I've never felt that "buzzing" that should be occurring when the valve operates.

Also, when I pulled the IACV out, I found a bare wire coming out of the harness behind it. I traced that to a female spade connector as shown in attached photo. I read somewhere about there being a grand wire attached to the IACV mounting plate and mine doesn't have one. Should the bare wire be mounted to the plate and then that spade connector grounded somewhere?

Thanks,

Vince