My Exploder had an irratic idle and a high rev(1200rpms). When cold for the first 20 seconds the idle was super rough then started to smooth out. There was twice I had a slight miss at WOT getting on the highway when cold. This all began to happen when it was getting cold outside. The main thing that pointed it out was the fact it changed when the engine got warm due to the gaskets expanding which sealed up the problem. Anyways, just wanted to give a scenerio to know what to look for with a plenum gasket leak.

I would clean your T/B if you haven't done so in a while. Also, change your PCV valve as that can have numerous effects on a vehicle.
You should throw a tuner on that and wake that 5.9l up a bit. HERE

 

Thank you! Are these tuners that good and worth that sort of cash? Do they really give that much extra bhp? There are other makes available is this the best?

Is there a thread anywhere here on these things?