I have a 1975 European 350 SLC with a four speed manual trans, eight cyl., and fuel injection. When I start up cold the engine races up to about 2500 rpm and then drops down to just about a stall and then right back up, etc. etc... If I can keep it from stalling out and get it up to about 3000 with the pedal, it will run steady until I let up on the gas, whereupon it will resume rollercoasting. If I disconnect the 2-prong lead to the intake horn on the air cleaner housing and jump it out, the problem will immediately diminish, only to resume as soon as I reconnect the plug. When the engine warms up, the effect disappears. The guy who sold the car to me was told that this was intentional on the part of M/B, but it sounds like a crock to me, but who knows?? Regardless, I need to eliminate this because it's almost impossible to drive until it warms up. Any ideas??