Mitsubishi Repair: Excesssive vibration of mitsubishi chariot model 1994 diesel engine automatic transmission, mitsubishi chariot, crank shaft

Question
I recently busted my timing belt.two fingers of the rocker arm were broken and replaced together with the belt. After this repair the engine has excessive vibration when idling at around 1000 rpm.when my mechanic reduced the idling at 900 the vibration have lessened but when i am accelerating and passes the 1000 rpm , the vibration increases but somehow will be gone at above 1500 rpm.when i decelerate, and the rpm passes the 1000 rpm on the slowdown trend the vibration becomes excessive again.is this timing problem?

Answer
Rolly,
The problem may be with the balance shaft or the balance shaft belt.  The belt is similar to the main timing belt, and keeps the balance shaft turning in the proper phase as the main crank shaft.  If the balance shaft belt is broken or misaligned, you will experience excessive vibrations.  
Good luck!