My 98 windstar 3.8 speedometer tacks in park when gasing engine up but goes to zero when put in gear. Then after driving it starts tacking again. Ford dealer mechanic disconnected vss, same problem. He could not find problem. Another Ford mechanic online said vss bad. If so it should set code, no codes. Cluster shop says cluster bad, wants $375 to fix. I need help. I bought a used cluster but not installed yet. Mechanic says you have to have computer reprogramed with another cluster.