1991 300e stalling after 10 minutes
have a 1991 300 E 2.6 after idleing for about 10 minutes the ca starts coughing and spitting and stalls out.Cannot restart until it cools down. I have replaced the coil,OVP Relay,Plugs,Cap and Rotor ,coil , Reference sensor,checked fuel pressure OK,O2 sensor and the car still does it.Seems like it quits getting spark,because when you do try to restart it backfires a bit.Any suggestions as to what this could be?I'm mechanically savy,but this one has me baffeled. Thanks for any help.

Mike