Rough Idle -- Only when Stopped in D
 

Alright. I read through the threads and could not quite find a direct answer to the problems I'm having.

1) The car has been running very rough when stopped at a red light and left in drive. When I put it in neutral the heavy shaking stops. This specifically happens prior to when the car has been warmed up. But I live in San Diego and it'll happen on an 80 degree day.

2) There is a hesitation when shifting from first to second then from second to third. By hesitation I mean the car revs a little then shifts to the next gear (almost too early before the rpm's should dictate)

I read that this could be a vacuum line issue but I'm having more of a gradual shift then a jolting shift. Also, its strange that the shaking only happens when the car is in drive.

What do you guys think?

Sorry. This is a 1981 300d

One last thing: It also takes about 30-45 seconds to sut all the way off after the key has been removed.

Well, it sounds like you've got some vacuum issues if it's hard to shut off. I'd start looking there. A mityvac will help you isolate where this is (by plugging lines and seeing what holds vacuum and what doesn't)

The bad idle could be motor mounts (what does it do in reverse?)

The shaking after hot is a typical problem.

These are the things that I had to do to tame my shaking in the order of what helped the most:
Rebuilding the Injectors; new Spray Nozzles Balanced and Tested (by me) took out the bulk of the shaking. Looked like at 198,000 miles I had the origional Injectors in the Engine when I bought the car.

Next best was doing the Valve Adjustment

Replacing the Motor and Transmission Mounts

Found I had a small air leak due to Fuel Inlet Hoses too hard to tighten. Only leaked air when Engine compartment was warm.

Fine tuning with the New Rack Damper Screw (it did not have much effect until I did the above list of things). No turbo= no Rack Damper Screw on your Fuel Injection Pump.

If you do not believe you have an Injector issue and all that other stuff

The Vacuum Leak might be effecting your transmission or it could just be wear.
Here is the other stuff on tramissions:
http://www.continentalimports.com/ser_ic20242.html AUTOMATIC TRANSMISSION ADJUSTMENT ARTICLE

WIKI Transmission adjustment
http://www.peachparts.com/Wikka/TransVacTune

Transmission adjustment Thread
http://www.peachparts.com/shopforum/showthread.php?t=158216

Definitely a vacuum issue somewhere.

You also probably need to replace the motor mounts.

There is no shudder in reverse, it only happens in Drive and only when stopped. Also seems to be getting worse and worse acceleration off the line

i dont think the shut off issue and the ruff idle are related. transmission flare and shut off could be related - vacuum issues/leaks. does your 81 have the idle speed control knob by the instrument cluster ? If so does it affect the idle ? idle issues could be caused by injectors, clogged fuel filters, air leaks in fuel lines.

The shut off problem definitely points to a vacuum leak. Buy a Mityvac and track down the leaks. You may have several. Do your doors also not open and lock after a few tries after the car has been shut off? They work on vacuum as well and if you have a leak, the rest of the doors will not unlock when you open the driver's door with the key.

After you find and fix the leaks, do exactly what Diesel911 laid out for you. Work through those items and I'll bet you solve the problem.

I need to do the same with my 84. I have fixed the vacuum leaks and adjusted the valves. Now I need to move down the list.

Yes yes ya'll. I found it. I had tighted the throttle linkage a few weeks ago and a metal rod connecting the linkage had popped off. After it was put back in place, the transmission doesn't pause, the idleing is a bit less rough and it turned off much quicker (though not right away). Still maybe a small vacuum leak and some dirty injectors but overall it is now much, much better.

Thanks for the suggestions gents