Well, that's always a good place to start. Replace the fluid & filter & see how it does but to be honest with ya once they start exibiting strange behavior the damage is usually done. It's probably WAY too late to matter but if/when you get the chance do yourself (and the truck) a favor and add a transmission cooler. If it's an AOD overdrive transmission *have the throttle pressure checked* the AOD's are mechanical overdrive trannys and the throttle pressure is critical. Once it's out of whack they shift funny then die. Bronco's had AOD's from 82' to 93' so if it's an OD transmission (you can tell the AOD from the C6 by the shift pattern on the dash if it's P-R-N-D-2-1 it's a C6, if it's P-R-N-OD-D-1 it's an AOD) so you might luck out and have an easy fix. How does the fluid on the dipstick look ? Is it pink or brownish ? Smell it, does it *smell* burnt, it's an unmistakable odor so ck it. If it's brown looking & smells burnt then change it. As a rule tranny fluid should be changed every 30K.