this happened to me a couple of times. when i start the truck, it wants to bog and die, i have to rev it to keep it running, its not willing to rev past 2,000rpm with out it wanting to self-destruct. the weird thing though is when i restart the truck though, it runs completely normal. what would cause that to happen? bad coil pack? cam positioning sensor? what?

for those who dont know, it has a 4.0 OHC

 

Weak fuel pump or plugged fuel filter.

 

My truck did this once about 2 years ago. I had turned it off then like 10 minutes later decided it was cold so I started it back up and turned the heater on. From the start it ran like crap and it wouldn't rev about 3K. I had plenty of gas so that wasn't it. If just started running like crap. I turned it off after like five minutes and started it back up. It ran fine and hasn't done it since.