1990 740 GLE stalling, gas in oil, running way too rich
 

I've got a 1991 Volvo 740 GLE. Starts fine and runs if you go wide open, but will stall when you let it back down to idle.
-puts out alot of smoke, also a strong gas smell in it
-just changed oil and gas is in it
-plugs foul very quickly

As far as I know the ECU was replaced with a rebuilt one, and I replaced the throttle switch, hoping that was it. I'm thinking might be fuel pressure regulator, engine temp sensor, etc but I'm a newb at Volvos.
Any advice? Thanks

RE: 1990 740 GLE stalling, gas in oil, running way too rich
 

Could be a bad regulator remove the vaccum line and see if there is gas in the line.It could also be a bad injector that is leaking.I would leave the coolant temp sensor for last to check.