Elusive idle speed

["tmasterlc" <tmasterlc@xxxx>]

Looking for input on an elusive idle speed. When started cold it 
sits between 900-1000 rpm. After about a two minute warm up the rpms 
step up to 1500 and the idle gets a bit rough (a little sputtering). 
Plugs, wires, cap, rotor have been recently changed along with vacuum 
lines and misc. other odds n ends. This problem has only come up 
within the last couple weeks and before that everything was fine. 
Have checked all vacuum hose connections for leaks and have found 
none. Micro switch is engaging and does kick down the rpm but only 
to the 1500 range. Throttle plates are closed and linkage is not 
hanging up. What puzzles me is the change as the engine warms up. 
Any thoughts

Car drives fine and accelerates through all gears without any probs.

Ron

P.S. Great show Ken.