fluffy idle ?

[Godfrey DiGiorgi <ramarren@domain.elided>]

I've rolled another 300 miles on FrankenSpider's engine. It's running 
very well in general, a pleasure to drive it. I've got two remaining 
niggles to sort out, however: a rattle in the exhaust and poor idling 
behavior.

The exhaust rattle was given one stab of repair and it seemed to stop for 
a bit, but now it's back worse than before. Seems to be some interference 
just about at the point where the LH rear trailing arm pivots. I'm sure 
this will be fixable easily once it gets onto a lift, but it is a bit 
annoying. 

The idle problem is a little more puzzling. Remember it's an '82 Bosch 
L-Jet engine setup. When it's cold, it starts right up and smooths into a 
nice idle in a few seconds, which rises slowly to about 850-900rpm when 
fully warmed. Sounds good, maintains that nicely no matter what. The 
problem arises when you park it for a little while and then restart it. 
It tries to die for first minute or so and then will idle at around 750 
rpm but stumbles, misses, etc. Drive away and four minutes later it's 
purring again. Once in a while, the stumbly fluffiness will just happen 
all of a sudden and then go away just as suddenly. 

Anyone have any idea where to start looking for the cause of this 
problem? The "usual" things have all been checked and seem right on 
(plugs, plug wires, various connections and hoses, etc). Seems to me to 
be a sensor that is heat sensitive... 

Thanks in advance.
Godfrey

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