Throttle problems, please help
 

I've got a 1972 Porsche 911T Targa, with Bosch Mechanical Fuel Injection. I've just recently got the car up and running after sitting for 10 plus years in a climate controlled garage.
Does any one know what would cause my RPM's to increase between shifts (yes, I'm letting off of the gas pedal). When I stop and shift the car to neutral, the RPMs come down within a few seconds to a reasonable idle. Any ideas?

Thanks in advance for your help.
:confused:

Have you followed your mechanical linkage from where it attaches to the pedal until it terminates in the carberators? I would lube the entire linkage, ensure the carpet is not interferring with movement, and check that no dust or wasps or other critters (mice, rats, etc) have built homes in or around the linkage or elsewhere on the vehicle. Start with the small, inexpensive stuff first and then work up.

Also check for missing, disconnected, weak or broken throttle linkage return springs. The linkage rod in the tunnel between the seats runs through three plastic bushings; these could be worn or disintegrating from old age (new bushings are available) causing excessive friction and a slow return to idle. If the linkage system is okay then look at the MFI system itself. Jim