2002 GMC Safari Van starting problem when the engine is cold

2002 GMC Safari Van mileage: 85,000. Within about six days, our van has rapidly developed a starting problem when the engine is cold. The temperature has dropped in the last few days making the problem worse. If the engine has run for a few minutes, you can shut it off and it will restart right away. My first thought was the fuel pump because it has the loudest fuel pump I have ever heard and now I can barely hear it. However, I can drive down the road, open to full throttle and the van takes off like it always has. This morning the only way I got it to start (it was fifteen degrees F) was to switch the key to ON for a few seconds and shut it to off, repeat two to three times then turn to start. Then it would start, but not quite as well as it normally has done.