I just bought a 1998 Land Rover Discovery LE and when Im around 45mph and accelerating, the car stops accelerating, rpm drops then goes back up and I'm able to speed up again. Any ideas on what's going on, and how to fix it?

 

Fuel issue most likely. Or air supply. Check the air filter first (easiest), then move to the fuel system. When was the last time you changed the fuel filter? Also could be some bad gas..lots of trouble spots in the fuel system. If it's driveable for you, try a can of Iso-Heet or fuel system cleaner, might help a bit.

It might also be the transmission/torque converter. Any noticable slippage anywhere else in the rpm range? Also is the loss of power ALWAYS at 45 mph, or is it at a specific RPM range in a certain gear or what?

Sorry for listing so many causes...but a little disambiguation never hurt

 

It's always at 45-50 mph, Doesn't slip anywhere else.