first off I own a 92 f150 5.0 302 5-speed std 4x4. one night I got stupid and went mudding with a couple buddys, and got stuck so I was driving her pretty hard. ever since that night my truck seems to have lost a lot of its bottom end performance. in neutral the truck will rev high right away, but in gear it takes a while for the rpms to rise.

here's a list of what I've checked already: -plugs/wire, rotor are a year old
-checked timing
-changed fuel filter
-checked compression
not sure what else to check, any ideas?

 

One or all of the cats may be clogging up.

 

thanks for the quick reply, i have been wondering if that could be the issue, but i don't want to cut it off and find out because i don't have a welder or anything. i took the o2 sensor out (thinking it would allow trapped exhaust gases to excape, but it was worse). is there an easy way to check it without removing it?

 

A muffler shop can check for clogged cats easily.

 

i took the whole exhaust system right off the manifolds and went for a drive and it seemed to have less power yet, does that mean my cats probably good?

 

Have you checked on a possibly clogged air filter or air inlet tube? Dirty throttle body. Possibly mud caked up on the rear drums or clutch disc? How does it shift?

 

i have checked the air filter/intake and cleaned the throttle body, i have also changed the o2 sensor and checked fuel pressure. i never really thought about the brakes being caked with mud but i've been driving it for a couple months like this already. i will lift the truck off the ground and see if there is much resistance felt later, in the mean time anymore ideas guys? we'll get it figured out yet!

 

i jacked up the front and back of the truck and all wheels spin freely, so i guess i'll keep looking for a solution

 

Check you're compression.

 

i checked compression and its good but i noticed when i pulled the spark plug wire off the #5 cylinder when it was running there was no idle change, does this mean its not firing? i know its got spark

 

How do you know it has spark? Pull the plugs and look at them.

If it were MY truck, I'd change the plugs, wires, cap, and rotor.

 

I would definitely perform a compression test. Also, one year old plugs, wires, cap and rotor should be replaced. If you installed budget grade parts store components, they might be due for a change. I recommend brass contact cap & rotor, low ohm plug wires and copper core Motorcraft plugs. It wouldn't hurt to replace a factory coil.

 

i pulled all the plugs and they looked alright, i think my truck has champion ignition parts, so it wouldn't hurt to put better on, what brand would you recommend for wires and cap/rotor

 

I personally would use Motorcraft wires, Motorcraft or Autolite copper plugs, and any name brand rotor/cap with BRASS contacts.

 

Or MSD Street Fire wires, MSD Cap & Rotor, and Motorcraft plugs. I have heard about a few issues with Autolite plugs over the past year from the Gen. 1 Lightning owners on NLOC.