E350 van/bus running issues please help!!!

[potenza]

Check the IAB. Also

Is that anything like a IAC, idle air control valve?

 

[harrycalahan]

Had a vehicle a while back with the same symptoms. Temp sensor was reading -140 degrees and of course trying to compensate by dumping fuel. I want to say it was an intermitant problem too like yours but cant say for sure.

 

[roundhouse]

Is that anything like a IAC, idle air control valve?

Yep
Idle air bypass

 

[roundhouse]

Had a vehicle a while back with the same symptoms. Temp sensor was reading -140 degrees and of course trying to compensate by dumping fuel. I want to say it was an intermitant problem too like yours but cant say for sure.

That's usually Chevys that fail and default to -140* F