[TR] TR6 Hesitation with high revs

[suhringtr36 at comcast.net]

I am experiencing high revs (3000 to 4000+ RPMs) with my '70 TR6 when I attempt to excelerate but the car does not respond until it gains speed.  I have had this before but it never lasted. It tends to happen more from a stop but can occur when I am in 3rd or 4th gear.  What are the thoughts on what could be causing this to occur.  TIA

Scott Suhring
Mechanicsburg, PA
'70 TR6
'59 TR3A