96 f150 xcab 4x4 auto 5.8l down shifts on the smallest hills with cruise control on any ideas? Truck has 3.55 gears the truck has a 5.8 with almost 330 ft pounds of torque should it be down shifting at 65 mphs?

 

I am going to guess you've got over stock tires......

 

I'm seconding rigrat..

 

It has 31x 10.50 tires on it

 

what's that in metric?

you should get back to stock tires, light LT ones, because anything after market has weight to it.

next, put a new air filter in your truck. just for s n g's

and if that doesn't work... go to a tranny shop and put a shift kit in it.

AND if that does't fix it... shoot the truck and get a coyote.

 

What's that in Latin? Oh you don't understand or care about Latin?

 

check for codes.

 

In metric it's 265 75 15 think I found it out cat are plugged!!

 

Do a vacuum test to find out if the cats are plugged. Hook up a gauge to manifold vacuum. Let the idle and vacuum reading stabilize on a warm engine. Rev the engine to wot then quickly release the throttle. The vacuum should go to near 0 then jump up over 20" when the throttle closes and return to normal. If it doesn't jump or slowly climbs from 0 you cats are clogged. If vacuum jumps then exhaust is fine.

 

I don't have vaccum gauges but I did that it and screen the codes and it was saying bank 1&2 o2 sensors so that makes be lean to clogged cats