My plenum didn't look bad either but it was factory. Not sure if it was mentioned but iirc people suggest to get the metallic gasket.

I came back to mention another '94 treasure. Egr valve. Tends to affect idle more iirc but can affect throttle.

My new engine didnt have a port so i deleted it by using an led light on the egr solenoid circuit. Some performance guys say no egr is better because its basically like eating your own poop. Speaking of food for thought... lol

 

Has your timing chain and gearset been changed? A stretched chain can rob you engine of power. If it hasn't been changed, please replace it with a double roller chain and gearset.

 

Did you notice any improvements from changing yours?
Can you please elaborate on the EGR valve affecting idle?
Lol, was actually talking to my dad about that today. Was wondering if I should delete it somehow?
I have not changed it, but it wouldn't shock me if it has been changed. The previous owner did a lot of work to the truck... Is there an easy way to check?

 

Just thought I'd give an update for future reference.
I changed my thermostat, MAP sensor, and cleaned my throttle body in one fell swoop. It now has HOT heat. It runs a lot smoother and doesn't cut out at idle anymore. It pulled quite a bit harder. Then, i did plugs, wires, cap and rotor, and noticed another increase in power. The old spark plugs had widened to around .64 gap, and the terminals and the cap and rotor were prwtty corroded. I haven't gotten to check my mpg yet, but very curious to do so. I wouldn't say it's as quick as my 01 F250 5.4 4r100 2wd, but it'll set you back in your seat now. What I find very interesting though, is that I went with my dad to test drive an 06 F250 5.4 3 valve (with only 30k miles on it since professional rebuild at 160k) 6 speed manual extended cab 4x4 last week. He had me drive it on the test drive, and, I know it's a heavier truck, but it had stock tires with 3.73 gears, as compared to my effectively 3.36 gears, and a whole lot more power on paper. My Dodge would have blown it away I think. Not sure what was going on.
Just thought I'd share my findings in hopes of helping someone in the future.
Courage