No one can diagnose a problem like this over the internet, because there are several possible causes. And if you can't catch it in the act, it makes troubleshooting even more difficult. And there are no diagnostic codes.

Possible problem areas:

- fuel pump relay
- idle control relay
- idle control valve
- throttle position switch
- lambda (mixture control) system

Try a search. Lots of posts on each of these.

A good basic health check is to see what the on/off ratio is doing. You need a meter with a duty cycle reading or an analog dwell meter. Again, lots of posts on how to do this.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe