Ok, i've officially done everything i know how to do to cure an inconsitant/rough/surging idle on my '86 240 DL. 104k miles. The car runs fine when in motion. When idling, i feel a hiccup every now and then and can see some erratic engine vibrations. Audibly, i can hear the engine surging slightly up and down.

Here's what i replaced:

- Distributor Cap
- Rotor
- Plugs
- Plug Wires
- Air Filter
- Air Intake Hose (that accordian one)
- Air Mass Meter
- A few cracked hoses
- New belts, shocks, and brakes...just because.

Other tests/maintenance:
- Checked for vacuum leaks at every hose and around intake manifold.
- Checked timing. It was set at about 12 degrees, dizzy turned fully CCW.
- Tried enriching and leaning the mixture at the AMM. No improvement.
- Tested the throttle switch. I get the "click".
- Cleaned the throttle body 100%.
- Sprayed WD40 in both ends of the Idle Control Valve. No improvement.
- Removed the thermostic valve in the air intake housing. It was previously stuck in position to only allow hot air from the exhaust into the system.
- All four cylinders are firing. Tested for spark on each plug wire.
- Ran a can of Sea Foam, a bottle of Marvel Mystery Oil, and two different types of fuel injection cleaners through it over recent months.

Other Info that May Help
- I bought this car in June. When i test drove it, it did not have this problem. The previous owner took it to pass emmissions before he sold it to me. I paid him. Picked it up, and then noticed the rough idle a day after the sale. Could the emmissions tester have altered something to get it to pass that would have had a detrimental effect on the car's performance? I asked the previous owner and he said that the only thing they changed was the gas cap.
- The previous owner apparently blew up the A/C unit by trying to recharge it with propane. I don't see anything connected to the A/C unit. Could the problem be here somewhere?


Ok, i know this is a long post...But for the last month i've really been struggling to get it to run as smoothly as i think it should.

Am i expecting too much? Should it be a little rough? Or is there something else i can test?

I sincerely appreciate any help than any of you can offer me...

Thanks in Advance,
Jon Zaremba