Okay so I have a 2001 F150 and I've lost something. If you pull up the drink holders in the middle console the whole plastic piece comes up revealing a great spot to hide things. So thats where I've been hiding things but recently something slid underneath a small opening underneath the cup holders and now I can't find it. Fine, but about 5 days later my truck is acting funny when its about to change gears, it starts shaking. Is there anyway that the piece I've lost could have slid down somewhere underneath the truck (via the hiding spot under the console cupholders) and is causing this problem?

manual or auto? console or steering shifter?

Yes it's possible. climb up under there and look around. Might also take the truck to an automatic car was and get the underbody cleaning. The water might losen the item and force it out.