Hello Folks,
I have a 2000 F-150 with a 4.6 V8 with approx. 35000 miles on a rebuilt engine. The thing seems to have no pep to it. It hesitates during acceleration and I don't even want to try towing my RV with it.

The computer has thrown no codes;

A vacuum check shows it running about 18.5 pounds of vacuum. When revving the engine, the needle drops to 0 and then shoots up to about 22# before returning to 18.5;

I tested the vacuum lines by using an UNLIT propane torch all along the vacuum lines with the engine running with no change in the idle;

Where do I go from here?
Thanks,
Chuck

 

The vacuum needle dropping like that is completely normal. I'd try something simple like checking the coil, plugs, wires, and air filter.

 

I was told by someone that I needed to replace the plugs with Motorcraft plugs. I am currently running Autolite double platnums. What is your opinion?

 

man 35k miles.. still new. when was the last tune up?

 

I really haven't tuned it since the rebuild. I have only done maintenance like oil changes, battery post cleaning, fluid level checks, etc...

Overall the truck has 338,000 miles on it.