Whats going on?

[benzman2]

Ok I have had this problem for a while now.

My 1987 300E seems to have a hesitation and shuddering when it is started up. Sometimes within the first mile or so the car wants to cut off but once u fiight thru the problem by giving gas it runs fine. This problem is worse when it is cold outside. I mean southern california cold like 60. I tried using chevron techron fuel system cleaner and it helped about 15% but the problem largely persists. Also the car sometimes when cold the engine races back and forth to 1500 rpm without me touching the gas.

Any help is greatly appreciated.

[lkchris]

ALL gasoline engines require a rich mixture and a little extra air to start and run properly when cold.

In the old days this was accomplished by choke and fast idle cam.

In your 300E same thing is accomplished by signal from temperature sensor to computer which activates cold start injector and idle air valve.

Vacuum leaks, however, defeat the attempt to richen the mixure and this is where you should look first. Especially hoses connected to valve cover and on each side of idle control valve.