Chevy & GMC Vans

I have been having a problem where the van runs really rough when it is really cold outside lets say 25F and lower. I can get it to start but have to pulse the gas pedal to keep it running. If I hold the pedal in one spot for about five seconds all of the sudden it just dies. To keep it running I have to keep cycling the gas pedal. Once started and running for a minute or two it will idle perfectly. When i push on the pedal to pull out it dies instantly and I have to pulse the pedal to get it to go forward. After a while I can slowly depress the pedal and eventually get up to full speed. Runs great on the highway at 70 mph with no hesitation.

Now get this. Today started out at about 25F and it ran horrible. When I left work at the end of the day it was 40F and it ran a little rough in the beginning (very mild), but after warming up it ran great with no hesitation or problems.

I have no check engine light. Any ideas where I should start looking?

Thanks

Had the same problem with my brothers 92 , it was the coolant temperature sensor located on the intake manifold next to the thermostat housing . the computer thinks the van is warm cuz the sensor is bad & runs like crap till it is actually warmed up .

Try disconnecting (& plugging) your vacuum line to the EGR valve.......

Have you checked for codes....?

Will try out the EGR and see if there are any codes stored since the check engine light is off. It does come on on occasion so I know it works. Ususally it is the TCC stuck code. My overdrive lockout doesn't work for now.

Anyway, tonight I went out and started it to make sure my wife wouldn't have issues in the morning. It kept sputtering and dying out. So after the last start I noticed that the fuel pump was still running after I shut off the key for about 8-10 seconds. (doesn't seem normal to run for so long after the key shut off, but maybe thats normal and just didn't notice it before) I then turned the key to the on position and I let the fuel pump run until it stopped. It was about 8-10 seconds. I turned the key and it fired right up. So I shut it off and each time it seemed to take less time for the pump to run. Next I started it and drove around the block and it ran totally normal with no hesitation. Normally it would buck and sputter until it was at running temp.

Confused at this point. I know it could be related to fuel pump. Pump is only 1-1/2 years old. I know that doesn't necessarily mean anything. Any other part of the fuel system that might not be functioning besides pump?