Thats fairly easy to do. First block the wheels so the vehicle will not roll. Put the transmission into neutral. Go under the car and on the drivers side of the transmission pan you will see the linkage. Remove the pin holding the linkage to the transmission. The linkage should slide in and out of the transmission shift bracket easily. If not loosen the nut on the linkage and adjust it until the linkage slides in and out without binding.
The 1993 Mercury manual transmission linkage will have adjustment nuts on each end of the linkage. Turning the adjustment nuts will move the linkage back in forth.
Linkage adjust
no adjustment on the 5speed manual transmission with overdrive. hydraulic clutch
usually a linkage problem - adjust linkage that connects transmission to gear shift
transmission is in but cant get linkage right. photo would help
Buy a Chilton's Manual for step-by-step instructions.
kickdown cable. it connects to the linkage on the carb's throttle. as the throttle goes in the kickdown goes out.
The adjustments are pretty obvious on the the top of the transmission under the air intake and exhaust plumbing.
To adjust the linkage on a toploader 4-speed transmission, start by ensuring the shifter is in the neutral position. Loosen the locking nuts on the linkage rods and adjust the lengths to achieve the desired shifter position. Tighten the locking nuts and test the shifter to ensure smooth operation through all gears.
How to adjust the linkage on cable from steering column to transmission on a 1995 GMC Van?
Sounds like you need to adjust the linkage.