the saga continues

This is my 3rd thread . First I had a rear main seal problem, then a confused injector (still unresolved) issue, now that the car is driveable the second to 3rd. shift (part throttle) seems to make the revs jump a couple of hundred rpm. Full throttle (power light on) shifts seem ok. Fluid is fresh and level is normal. Tranny was rebuilt 14k ago, with a 12k warranty..... my luck.. do any of those limited slip additives I see at auto parts stores help here ? thanks again. Yes, If I could afford a new one I would get one, but the 2.2's still seem better than the 2.5's especially for me, I drive 1000 miles a week.