There are a lot less external adjustments on a gas motor's automatic transmission.
I do not understand your symptoms, but I fear that you may have a totally separate problem; fuel or ignition related. To verify, try shifting totally manual. Start out in 2 and only shift out after you have accelerated. It is unlikely that acceleration while held in gear will cause such a loss of grip as to be the way you describe.
Can you check your manifold vacuum?
Bosch Master, ASE Master, L1
33 years MB technician