Sounds like the fuel is leaking down into the intake when the car is sitting.... then it takes awhile ti burn off the extra fuel... check that the fuel pressure isn't dropping when it is parked....
1991 Ford Taurs SHO 5 Speed White on Tan
1996 Chevy Lumina LTZ Rep 3.4L
1992 318i Coupe parts car
1992 325i Ls1 swap with a T56 6 speed 12.2 quarter mile
1976 Mercedes Benz 300D with a Ford 5.0L Fuel Injected soon to be Modded I am Captain Obvious