What are you calling a speed sensor? The sender for the Speed O back on the TC? If so, no, it shouldn't be loose. HOWEVER, that has nothing to do with your tranny slipping. If your Jeep has a power/comfort switch...and you haven't done it yet....put the switch in the power position and leave it there. If you've done that already or you don't have the switch then, your tranny has internal clutch issues.
Brian "Buck" Buchanan, U.S. Navy Chief Petty Officer (RETIRED) - 87 XJ Laredo, Ol' Red - 8.5" Rusty's Offroad/Rough Country lift, D30 trussed and D44 high clearance shock mounts, 4.56's, Aussies, Chromos and Disc Brakes front and rear, JCR Offroad Belly Skid Plate and Stage 2 Rock Sliders, Off Road Fab Winch Bumper and Quarter panel Guards, Liberal Front Wheel Well trimming and Rear Wheel Well Cut N Fold, 35" Goodyear MTR with Kevlars, Cobra CB and AW4 First Gear Lock Crawl switch, SYE, Stock XJ driveshafts front and rear and Milemarker SEC8000 Winch.
91 XJ Sport (Old Gray Jeep) - Layed to Rest (04-01-13)
87 XJ Laredo (Ole Red) - (My Jeep)
87 XJ Base (The Boys Jeep)
96 XJ Country (The Daughters Jeep)
08 Dodge Charger R/T (The Wifes Ride)
04 Silverado 2500HD Duramax/Allison (tow rig)