I know its a different beast, but the gp light on my 90 300d just started doing the same thing. It also uses no gp fuse. After testing i found 1 of my gps to be bad. Still starts, it just takes a few secs or so for the idle to smooth out.

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VegStew
1983 300SD 70,000 WVO Powered miles
1990 300D In driveway with Head Off - Cracked