2003 Isuzu Trooper Jerking @ Takeoff

#1

My friend has a 2003 Isuzu Trooper w/ on demand 4x4. It had a slight jerking @ takeoff before he changed the transmission oil. The problem is now worse. It feels like he is going over railroad tracks. It only does it while he is taking off. Does he need a new transmission?

#2

When was the last tune-up?

#3

15,000 miles ago, but it doesnt misfire . . .