revs high but takes time to get going???

I have a 1991 G20, 5 spd manual and just recently started having this problem. I can change gears with no problem but when I get into a different gear, I give it some gas, the engine revs high but it takes a bit of time to actually get moving. Any ideas what it could be? I've looked through this forum and it looks like it could be several things (clutch,oxygen sensor, ECR valve, tranny......). Any help would be appreciated.

Thanks

Does it feel like the clutch is not engaging? It sounds to me like it's a clutch problem.

That's what I was thinking. I'm going to take it in to get it checked.

Thanks