So I've been noticing lately that my 03 FX4II has been doing this weird bounce/hop when driving. Every once and a while when driving at a steady speed [35-55mph] it will suddenly hop or bounce. It's as if I went over a little bump or the truck got pushed from behind. Any idea what could be causing this?

 

 

Bad tire will do that, band inside is separating, but that should be a steady bounce at certain speeds

Check fluid level in BOTH axles/differentials

Get under it and move parts to see if any are loose

 

If its doing what I think from How ur explaining mine did that and when I cleaned my maf sensor it stopped. It came back thou cause I had a aftermarket air filter on it. Changed back to stock and it Ran perfect.