8O Hello everyone. I just got this 84 caballero with a 305 engine and and automatic transmission. The car runs pretty nice, but it's a little sluggish between gears. Does anyone know what could be wrong (yes, there's fluid in it)?

If the tranny is not shifting at the correct time, first check the vacuum modulator valve on the transmission itself. It may be leaking. Often, when you pull the vacuum hose off the modulator valve, transmission fluid will drip/run out of the hose. That is proof positive that the valve is leaking and needs replacing. It's easy and inexpensive because it just screws in. Second, if the transmission is not shifting on time (too early or late), it could be that the kick down cable needs to be adjusted. This is easy to do, if you know how. If you do not know how to adjust the kickdown cable, hire an honest mechanic to adjust it for you. It can be done in about 2 or 3 minutes, so do not let a mechanic keep your vehicle overnight so they can adjust it while you are not looking. Most of these guys will charge you $40.00 or so for those 2-3 minutes of work. Finally, it could be internal problems just beginning with the transmission. Fix 1 & 2 can be done quickly and inexpensively. Try them first.

I would take it to a good transmission place and have them back flush and change the fluid before I spent any additional cash on another or a rebuild. The flush will run you about 80 to 105.00 that backflushes the old fluid completely out of the transmission replacing it with fresh. The cost is for the 14 or so Qts of fluid the transmission and torque converter hold and they do replace the filter and pan gasket.

Then if it doesn't clear up I'd look into a re-build of all the Soft Parts. Do the Modulator valve check too it doesn't cost anything to check it. If its been leaking into the vacuum line then its also getting into the intake manafold and can burn the valves in your engine.

Thanks a lot for the info, guys. My dad and I are going to do some work on it over the weekend, so hopefully it will be running nice and smooth by next week. :)

I would take it to a good transmission place and have them back flush and change the fluid before I spent any additional cash on another or a rebuild.
The owner of the transmission shop I deal with will not flush a transmission. He says it will only cause more problems and it's better to just change the fluid in the pan along with the filter. Most of the franchise tranny shops like AAMCO and Cottman will encourage people to flush the tranny.