Hi everyone!

I have a 1997 Ford Ranger XL 3.0L V6, I recently bought the car with 117,000 miles and have experienced poor acceleration. Since I got it I have replaced/ worked on any and all issues I thought may contribute to the poor acceleration. I had a mechanic give the car a clean bill; no work is needed for the engine. However, when I accelerate it is very resistant and sluggish, the gas pedal makes a loud "rattling" noise (even though it's been tightened) and it struggles to go over 65mph or up large hills. I realize it's an old car but considering it's a V6 truck I'm very confused, I've driven many other trucks and rangers around the same year without this issue. Also the throttle body assembly "spring" is loose/not engaging, I thought that was the problem but the mechanic said no. Please help!

Here is the work I've done:
-spark plugs+cables
-accelerator cable
-oil change+filter
-air filter
-valve adjustment+valve cover gaskets
-fuel filter
-shocks+wheel bearings
-fuel regulator


This is the spring mentioned in the post!

This is the spring mentioned in the post!

This is the spring mentioned in the post!