My 96 850 is very difficult to start and, once started, the engine runs rough for a minute or two. Meanwhile the idle varies from about 500 RPM to 1500 RPM. The idle then smooths out, as if all injectors and plugs are working properly, but the variable idle remains for 10-15 minutes. No codes have been set. Based on the mechanic's educated guess, the RPM sensor, cap and rotor were replaced. Injector cleaner last run through the fuel system about 10K miles ago. I plan to do this again now. There does not appear to be any vacuum leaks. The only other component which I believe affects idle is the air mass meter. How can I test it? Any other suggestions for troubleshooting. Thanks for any input.