My 81 Cordoba (110,000 mi) has a problem with transmission. When I am driving it, it will shift into the right gears, but after it will appear to be in a not engaged clutch position. While "cruising" on the highway I step on the gas to maintain my speed and it will race before engaging power to be drive train, sort of like I had put the shift in neutral and then returned it to drive. There is a solid engagement when engages, no slipping, etc. If I leave it number 2 position this does not happen. Someone mentioned a weak spring, but not what spring.