98 venture hard starting problem

i have a '98 venture that starts hard only on cold start-up or letting sit for a number of hours. it will start like this every time. if you start the engine after it has been running, it will start with no problem. on cold start-up the engine will start and immediately die over and over again unless you give it just a little gas while starting. it almost acts as if the engine is not idling high enough when starting. it also smells as if it is running rich. after about thirty seconds of toying with the throttle it will run fine and run fine all day. the problem seems to be worse when the weather is cold. it occasionally throws a bank#1 too rich code. i have replaced the upstream o2 sensor, iac motor, fuel pressure regulator, tps sensor, fuel filter, temp. sensor, and have monitored about every other sensor i can think of. there doesn't seem to be any other engine running problem other than starting. my last guess would be an injector problem, but the engine runs out just fine. any help on this problem would be greatly appreciated. thanks.

Make sure you've checked the fuel pump plug as noted in other 'trouble starting fuel' posts such as this: "mmorales--Be sure to check the plug underneath the driver's side sliding door. Look under the van and you should see a couple of plugs going into the body. One is smaller than the other. The smaller one is for the ABS system and the bigger one is for the fuel pump. I had this problem and all I had to do was unplug the fuel pump clean out the connectors and plug it back in. The van started with no problems. I have had problems since then though. The van starts and runs but it hesitates and has trouble idling." Its worth a shot!