My 1999 magna solar is shuddering when going from 4 th to 3rd gear usually on an incline, and stops when I take my foot of the excellerator
Bring it to a shop and ask for a transmission flush. Make sure that when filling the transmission back up that they only use Mitsubishi Diamond ELC-4 SPII Fluid (V6, 3.5l) or check your owners manual and use the correct Mitsubishi Fluid for your model. Using any other fluid will result in damage or bad shifting. Have you had your fluids changed recently? If so, did they put in the proper fluid?