Joining up here with the first objective being to get help on this issue. I've found some discussions online elsewhere, but they seem to end without getting to the cause and solution.

I get a low level, somewhat high frequency, vibration on acceleration from a stop, about when engine hits 2000 rpm. At constant speeds, there is a light buzzing or tingling that can be felt in the steering wheel and the accelerator pedal. The engine seems to idle normally and feels smooth enough when moderately revving with no load on it. Truck has 165K miles and this started at maybe 145K.

Thanks for any guidance.
Charlie

 

Welcome to the forum

There could/would be many causes for what you describe

Can you feel a vibration when parked and raise RPM to above 2,000 and hold it there?
4cyl engines are notoriously bad for vibrations, they only fire every 180deg of crank rotation

Check motor mounts
Hood open
Parking brake on, or tire blocked on both sides
Engine at idle
Put in 1st and let clutch pedal up slowly, engine should rise up a bit on one side, push pedal down fast and listen, should be no "cluck" or any noise at all
Repeat but in Reverse this time

Check u-joints, if it is a u-joint it may be too early to feel it in manual test, you can replace them on speculation

Have drive shaft balanced

Have tires Road Balanced, this is done on a machine that puts pressure on the tire, like it's "on the road" while they balance it

Get a 4 wheel alignment