Finally fixed the issue of my fuel pedal not returning. The problem in the end was the fuel pedal itself had no spring action left in it's own operation. It was pretty gummed up, all the throttle linkage was mucked up too. Parts to replace were not expensive from Unipaser and EI except the Fuel Pedal itself ($93!) and Michael from Unipaser told me I needed spring behind the fuel pedal. The Shop manual for the 404s does not include a diagram with this spring. I found it in the Teil 5 TDV2320 (page 102) Military Parts Guide though. Here's a screenshot.
Apparently some models did have this spring and some did not. Page 107 in the Teil 5 guide for the Fuel Pedal show my original configuration, while page 102 shows it with the spring. Maybe it was for the 404.0 or another model. All I know is that spring is making all the difference for this 404.114s
The fuel pedal comes with the elbow and nipple for throttle linkage already attached (don't let that picture above fool you, that elbow does not come off). The pedal has to be swung towards the engine to get the angled elbow out of the little hole in the chassis. Don't do what I did and hack out the old one with a saw and nick my oil gauge line (that part is no longer available).
The lower right footwell panel (that sit's under the doghouse) has to come out. The drivers seat and right support rail has to be removed first, then the panel. I don't think on my 404s this driver side footwell panel had ever been removed, no amount of Acetone / AFT mix would loosen these screws. Some had to be drilled out and the holes re-threaded. Once that was done, the new pedal went in without an issue.
If you're ever unlucky enough to replace the fuel pedal, you'll need one person in the cab with a wrench and another underneath with another wrench to work the bolts.
The other item to watch out for is the return spring that came on the truck is bigger than the replacements you will get currently. The newer spring looks smaller, but it works just fine. The cross over shaft has 2 plastic inserts on in each of the steel tubes, don't lose these. I used a 22LR cleaner swabs to clean the tubes out of muck.
I fired her up and after she warmed up, the fuel pedal and throttle linkage are all working as they are supposed to. Hopefully I can put this one to bed for a while.