I have a 1991 940 16 valve that starts and runs fine from cold. Once engine is up to temperature everything is OK until engine is stopped for a few minutes. Then engine will just restart and idle very roughly and will stall as soon as throttle is depressed will not run above idle speed. I have replaced impulse sender, resoldered fuel injection and radio suppression relays, changed inlet manifold gasket, new distributor cap, rotor,leads and plugs, new fuel filter, cleaned trottle body. Both fuel pumps can be heard running. All have made no difference. Have run out of ideas now, can only think some sort fuel vaporisation or possibly coil problem? Help!!!