Klaus,

Sorry for the delay in getting back to you have been tied up in the office. As to your first question did the relay #3545803 make a difference? In my case no. When I replaced it I did so as to “cover and the bases” I knew the IAC was getting power because I could hear/feel it running. It was not that expense ($20) so I put it in. As to it running the IAC I had the same question about which relay after read post on the Brickboard. So contacted: http://www.thepartssite.com/ after some searching they told me that the relay runs both the fuel pump and IAC. I never did confirm this. But to do so would be easy. Turn the key to run don’t start engine. You should be able to hear/feel the IAC running if IAC is not completely dead. If IAC is dead you would need to use volt meter. With key in run position and IAC running (ie: voltage present) pull the relay if IAC stop (voltage gone) then the relay is running the IAC and fuel pump. Hope this helps Brent
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1994 850 WAGON NON-TURBO B5254S/SS ENGINE 2.4 LITER 5 CYLINDER. AUTOMATIC 4 WHEEL ABS 114K MILES