My '92 F-250 with has an A40D automatic (I think thats what its caled). The transmission was re-built at 87,000 miles. The truck now has 105,00 on it. Lately it has been what I would say "surgung" or "lurching". For example, you coast up to a stop sign and it "lurch" ahead. I talked to a mechanic about it and he said it is most liekly something called torque lock, meaning one of the valves in the torque converter has dirt in it / is sticking, thus the surging/lurching. My question, is there some kind of attitive I can add to the trans. fluid that may help this problem.