'91 525i M50

Help anybody!! My '91 525i will start up & run fine but will die on idle-- upper rpms are ok! after warmed up, maybe 2-3-4 times, starts right up again each time. Replcd already- Idle cntrl vlv.- fuel pmp relay-- throttle pos. switch--- dme relay, dunno what else to replace?? --Runs great otherwise!!! Does anyone have any ideas? Thanx Davypea