My truck has developed a slight vibration at idle. As soon as you take it off idle it goes away. I'm getting ready to go out and check the crank pulley and balancer, is there anything else I should be checking? Could the belt tensioner cause a slight vibration?

Mechanical viberation would stay at higher idle or when in gear @ idle or above. Engine mounts could be a problem,not dampening. Fuel interuption/irregularity to one or more cylinders would be my guess. How much time/miles on the new injectors?

only about 6000 miles on injectors

My truck has developed a slight vibration at idle. As soon as you take it off idle it goes away. I'm getting ready to go out and check the crank pulley and balancer, is there anything else I should be checking? Could the belt tensioner cause a slight vibration?

Is the vibration resonating in through the dash or is it a mechanical failure type of vibration? Things tend to get loose over the years just from the harmonics of the engine at idle.

I would start by removing serpentine belt and see if the vibration is gone, if it is then start checking everything driven by belt. If still there then look very close at the harmonic balancer and pulley.:cool:

My rough idle was from the crank pulley and balancer, made a loose rattling metal noise also at the time.

Removed the crank pully and checked it and balancer and they are both fine. The vibration is like what Snowdrift described above as resonating through the dash more than a mechanical vibration.