Wacky, Strange, Curious Idle
 

1976 450 slc 144,000 mi. Los Angeles CA. avg temp 40f. - 70 f.

Idles rough (misses and sputters) especially in the am when first start. Almost undriveable till temp guage reaches 178 or so.

after warmed up-
Problem is exclusive to idle. If put in neutral tach raises and purrs perfectly. Drives fine when tach raises 10-15 rpm's or so.

My Mechanic (mike Mercedes Burbank Ca: Excellent) has tried numerous fixes to no permanent solution:

> Replace fuel distributor with rebuilt
> check all fuel injectors (CLean)
> Fuel Filter replace (probably other incidental stuff I'm not recalling)
> Fiddling with idle rate under air cleaner ( this works partially for a couple of days, then it reverts back to original behaviour)

The car has been kept up well and has been serviced religously from the beginning.

Thanks in Advance for any help or clues