[jdmccright]

Sounds like it could be transmission related. When was the fluid in it changed last? When warm, is the fluid at the proper level and what color is it? Does it look brown or opaque? Does it smell burned? If so, it needs to be changed. If you take it to a repair shop or a fast oil change place, DO NOT OPT FOR THE FLUSH. They may push you saying that since you don't know when it was done you should do it, BUT DON'T. Do a regular fluid and filter change.

[Side note] - You want to get the old fluid out and a flush is supposed to do that, but what it also does is break loose the years of varnish and build-up inside the valve passages from the years of neglect...in your case it is presumed by the previous owner. These floating particles get lodged in the valves and critical passages and cause failure. The better option is to do a regular fluid and filter change, then do it again about 500-1,000 miles later. This will remove most of the old fluid and allow the sludge and varnish to slowly redissolve.

Is the "Check Engine" light lit up? Has the "O/D Off" been blinking recently? These would indicate trouble codes that have been stored in the car's ECM computer. Even if they are not lit now, the codes are still stored. Find a nearby parts store that will read your codes for free with their scan tool and post back what you find.