The throttle body plate at the butterfly valve is exceptionally clean. In Ontario, we have drive clean emissions testing and the car performed exceptionally well there as well. Low NOX.

I believe this stalling is now related to fuel pressure or supply more and more.

What do you think I should have done?

A. Go with a diagnostic service?

B. Go ahead and replace fuel pump relay?

I am thinking fuel pump relay more and more. Car hums when key is on... Car starts fine and will actually idle like silk. Coming to a stop causes it to stall.

Fuel pump relay or throttle microswitch?

Please advise guys.

Thank you

Mike McKinney

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1989 300CE - 269,000 km
1994 SL600 - 59,000 km