Minor glitch with my 727....

I took my car for a drive today, and once I hit the 2,000 RPM mark, the tranny shifted itself into neutral what it seemed like anyway. Because all it did was sit there and rev, until the RPM's when back down to under 2k.

It also did it, going up any hill, steep or not, even under 2,000 RPMs

I've never had a problem like this, any advice?

I have already checked the fluid level and it's good.

I have also developed a grinding/buzzing sound coming from the trans when I put it in reverse. Only started doing that AFTER a friend broke my cable for my B&M Shifter.(I have the cheetah just haven't installed it yet).