It all started after the overheating issues I had...I ran the car at ~110C a few times while trying to figure out what was going on. I used the heater to keep temperatures down, but it never hit the red line.

Water pump and radiator later it is resolved and now purs at no higher than 95C in 115F heat here in Phoenix.
Could the overheating have done anything else?

Car idles smooth, no misfires....I have dropped from ~20mpg (~300mi to tank) to 12-13mpg (210mi to tank)

I've done a full tune up in the last 5k miles when I bought the car. All filters and fluids, rotor, cap, plugs wires, ovp...Duty cycle is ~45-50%.

Car drives fine although power seems slightly down, but nothing else out of the ordinary.

Any ideas how I can track down whats happening?
For my 87 260E

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