Not sure, but occasionally my 1985 380SE will do this (stalling) when the engine is fully warmed. It did it once today when I was pulling into a subway. I made a turn into the parking space and it stalled when I was turning into the space. I coasted in and turned it off. It always restarts normally. Sometimes it will also stall out when I shift into gear. The "tapping" of the accelerator and stalling is not an issue on my car however.

I have been told that it is probably the idle control solenoid, but I am sure that the 1998 is probably a different setup? Not sure, but it may also have a similar valve that is your issue?

Good luck.

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2004 Toyota Sequoia Limited 4wd
1991 Lincoln Town Car Executive
1991 Cadillac Sedan DeVille
1988 Mercedes 300SEL
1972 Chevrolet Caprice Kingswood Estate 9-passenger wagon
1973 Pontiac Grand Ville
(Prior MB's: 1974 240D, 1985 380SE, 1984 190D, 1993 400SEL)