I had an awful time restarting my '94 850 after starting it cold and moving it a few feet to cut the grass. That short time of running did not get the spark plugs hot enough to avoid fouling at the next attempt at starting. This may be your cold-start problem..you need at least a couple of minutes of running to get the plugs hot enough to not gas foul.

On the hot start, check socket A2 for codes. My 850 also did this and in my case, it was the cam sensor...but there are any number of sensors or problems that could cause this, and the best bet is to check those codes first. I agree with everyone that suspects the fuel pump relay, but since you say you have fuel, I am more inclined to think of a sensor failure.