Well, my truck has begun having random misfires occasionally, it acts like its dragging several deads, but I've always gotten it to go away by letting off the throttle, then it will go away. It has a lurch when idling under load (i.e, idling in gear), and I've noticed my gas mileage has tanked, to 8.5, down from 10, but the computer isnt throwing any codes. If it's at all related, the cruse isn't working either, the light comes on, but will not set.

 

Cruise is likely a separate issue.... maybe.

The V-10 is a smooth running engine, to the point that even with a dead miss, the PCM never figures it out...... When is the last time it had a tune up? How old are the plug wires?

Start with looking for vacuum leaks. I *think* the cruise module is under the battery tray, and it is notorious for getting eaten up by battery juice......

 

the last full tune up was a couple years ago now, and the plug wires are 5 years old, according to the carfax on the truck. I'm pretty sure it's due for plugs as well. How hard is it to pull the battery tray out?
EDIT: it also does lope about 50 rpm at idle

 

Major pain to pull the battery tray. Two bolts on top, two under the battery, and two more down on the inner fender well, with a little bracket with studs. The nuts seize on the studs, and you end up twisting the little bracket into a pretzel, and breaking it..... Liberal amounts of PB Blaster may help...... Maybe.....

 

Well, that ought to be fun. What part of the cruse module gets eaten up, is it the lines or unit itself?

 

The unit itself. Think I would test for vacuum leaks there first, before going thru the pain of pulling the battery tray. (and also verify that it really is under there.... follow the cable from the intake, see where it goes. Been a while since I have been in there... I may be misremembering. )

 

alright, thanks. How would I go about checking for leaks, by spraying some either down there? And is there a brand of unit that I should avoid, like some sensors that dont play nice with these trucks?
also, is the 50 rpm idle lope possibly part of the issue as well?

 

Your idle lope likely is from a vacuum leak. I would just unplug the vacuum line up by the manifold, and plug the port, see if the idle smooths out.