i just replaced the plenum gasket on my van with the 318 now wont idle and dies as soon as you put it in gear? what did i do wrong?

 

Disconnect the battery for 10 minutes, then reconnect it and see if the idle is better.

 

when its cold it idles fine but when it warms up it wont idle when the pcm is reset shouldn't the engine light go off?

 

Yes, if you reset it with a scanner. Simply disconnecting the battery will not always turn off the CEL. It depends on what code turned it on in the first place.

As to the no idle when hot thing, that can be caused by a bad coolant temperature sensor (CTS). It's the 2-wire(PCM) one, not the one-wire(gauge) one.