It can be the trans but it can be the engine as well. The trans downshifts resulting in the rpm going up but accelerating power is lost then.
Does the rpm shoot up very high or only goes to a certain rpm and holds while the vehicle struggles to gain speed?
Is the MIL indicating and have you checked for trouble codes?
If EGR is used, check that.
Sunday, August 5th, 2012 AT 4:11 AM