>On Mar 16, 11:13 am, Mike Romain wrote:
>> I had an 85 Coronet with the same sounding trouble. It was intermittent
>> and wouldn't show when my mechanic had his head under there. Drove us nuts.
>>
>> We were doing something else unrelated and I was farting around and
>> pulled the vent line off the carb's float bowl. The RPM instantly
>> changed. It isn't supposed to...
>>
>> Turns out that was my first run in with a dirty air filter on the gas
>> tank vent! There is this $2.00 filter that goes on the bottom of the
>> charcoal canister that is supposed to get changed every major tune up.
>> The first one is a bear to dig out, but subsequent ones just tuck in and
>> out.
>>
>> When plugged, this canister does the neatest imitation of starving for
>> and up and running out of gas by creating a vacuum on the gas tank and
>> carb float bowl.
>
>This is a very uncommon fix that I have heard a lot about recently.
>>From EVAP trouble codes to not being able to fill a gas tank. I wonder
>how many problems have been fixed by replacing this little filter??
>
>Definitely a technical gem.

I had an 80 Plymouth bought new at work that started doing that at about 90K miles. They replaced a lot of parts and never solved the problem so they sold the vehicle. One of the nicest vehicles I've ever had - I hated to see it go.