I have a 1993 Plymouth Laser. It is a 1.8L, 4-cyl, 5-speed manual. I just replace the transmission with one from a junkyard. The other transmission had a hole in the case and had lost 5th gear. The care drove normal other than the fact that I didn't have 5th gear. After I replaced the transmission, the car now lurches in first and second gear when the car is cold. It also lacks power in first. What could be wrong? The only thing that has changed is the transmission and the gear oil. I am using the recomended type and viscosity for the climate. Should I go to a thinner oil?