I also had a rough Idle problem with my truck after doing a tune-up and it turned out the factory gap in the after-market plugs was .044" , I found out later thru some surfing and correction reference the FSM that the 3.0 is supposed to be a .031" gap , re-gapped the plugs and idle smoothed out drastically and acceleration and throttle response improved also , not saying that is your problem here but may help you if you installed aftermarket plugs without checking gap like I did .

 

Have you checked to ensure proper spark plug gap?

I have read a couple of posts where people have had similar issues (myself included) where re-gapping the plugs fixed the issue. I will be checking mine this weekend trying to fix a rough idle / miss at low RPM problem. It feels like it is missing when stopped at a red light, and for the first couple of feet after take off, then it clears up and runs like its supposed to. It doesn't act like it's missing at speed under hard acceleration, so I know all cylinders are firing, just not firing good at low RPM. It could also be a vacuum leak or something else since I too recently had HG work done. This is where I plan to start though.

 

That is what mine did and it was a combination of the plug gap , vacumn leak(idle adj screw o-ring bad) and the TPS .
The TPS was responsible for a bit of a stumble/miss off idle and even a occasional spit through the intake , I tested the TPS and it was open all the time on the terminals that controlled the VAFM so the ECM would have no idea of how far open the throttle plate was , also it was open when at idle on the other test point so the ECM never knew it was supposed to be on the idle circuit .

 

Seems to have the same amount of power as it always has, just a little problem with Idleing

 

Have you tried SeaFoam through the intake? Maybe somethings plugged instead of leaking. It smoothed my idle out a bit the first time I did it.

Malfunctioning EGR valve will make your engine act like it's got a vac leak too.

 

yeah, no problem with power, just a little stumble when you first start accelerating then it gets a kick in the pants and goes. If it weren't for that, I wouldn't even bother troubleshooting it, I would just chalk it up to rough idle.

 

Here is the PDF Link from the FSM for testing the TPS if you need it:
http://personal.utulsa.edu/~nathan-b...93throttle.pdf
MudHippy is right about the Seafoam , I used a can with 8 gallons of Premium in my tank for the injectors,valves and combustion cleaning and then I bought a second can and sucked it up through Throttle Body Vacumn Line and it helped alot .
I know I left a different in a previous post but am trying to use the FSM now as much as possible .

 

Before you touch the idle screw clean the throttle body with a toothbrush. Make sure you don't use carb cleaner as that can damage the O2 sensor. Mine has idled low below too - carbon buildup in the passage that controls the idle that the idle screw is set into. Try that before you start changing any thing else.