Hi have '91 GTA (automatic) and i've had it for about a year now and while cruising at low speeds it shifts into second rough, kinda like a jerking motion. it only does it while driving at low speeds for instance if i am accelerating it shifts smoothly. The seller said it was because it was of the 2500 stall converter it has but it getting very annoying and i've been wondering if this is true or are my transmission mounts bad? thanks..