95 pos 4runner helpp me

i own a 95 toyota 4runner i know very little about auto mechanics but fortunately my roomate does. ive own the truck for less than a year and have had many problems. one probelm is my trans. every once in a while it wont go over 40 mph @ 5k and trans is screamin..if i disconnect the battery it fixes itself for a little while. any ideas? 2nd problem major loss of power in the truck. changed plugs, plug wires and air filter. hollowed out the cat thinkin it was clogged but truck still runs like poop lol. please help me i will love u 4ever lol i jus want my truck runnin rite!

Try changing your engine thermostat. Your transmission will act very strangely with a thermostat that never closes.

Flush your transmission if you haven't already done so.

Do you have a "Check Engine" light on all the time?

thanks for the fast response bri. check engine light is on id say 90% of the time. also at about 30-40mph at about 3k it clunks. i hear a bangin noise and it feels really close to the deadman pedal on the floor. thanks again 4 ur help. im changing the fuel filter tomorow. do u think it could be a speed sensor or mass air flow sensor?

Get the codes from the check engine light.