Transmission problems PLEASE HELP
 

I have a 1994 s10 blazer 4.3 and on my way to work last night without warning it started not wanting to pull... I could feel it shifting up to35 mph or so and then any more pressure on the gas pedal only resulted in the engine revving like I was in neutral... Can't get it to accelerate.. I parked it and shifted through the gears and it seems normal shifting to reverse, neutral, drive, etc... But like I said once I get to about 30-35 the engine just revs? Please give me some suggestions.. Thanks in advance

Start simple. Check dipstick with blazer running. Is trans low on fluid. Smell the fluid to see if it smells burnt. Not red but dark brown color...