Tranny problems

Yesterday I did an oil change and tune up (spark plugs and wires) on my 93 explorer. I checked my transmission fluid and it was full. I drove the truck a couple of blocks away and parked it. I left it running. Five minutes later I got back in the truck and put it in gear and accelerated and it just crept I got up to 2500 rpms and I didnt get over five miles a hour!!! It does it in every gear, Drive, overdrive, drive 1 and 2. Even reverse!!! Could it be the transmission filter? The torque converter? I NEED HELP!!! PLLLLEASE!!!!!

It is a automatic with 4 wheel drive auto hubs