2000 Hyundai Accent 1.5cdx - noise on revs

Hi
This is now doing my head in, everytime I start the car I have a steady
rumble coming somewhere from within the dash or inside the trim.

When I speed up the noise gets worse upto around 50 miles per hour and it
only goes away once the car is in 5th and going at around 60ish.

I have had the whole dash off felt around inside to see if anything I
touched changed the way the grumbling noise sounded but nothing, I have been
under the car but again can find nothing, I have been under the clutch and
other pedals to see if I can change the type of noise but nothing again.

I have totally no idea where its coming from but it does have a very slight
vibration on the clutch and gas pedal.

Anyone with any ideas at all because this is making me want to give up and
sell the car.

 

I witnessed an Accent of about 1995 vintage with a vibrating power steering
line that sounded like it was coming from the dash.

Does it happen only on acceleration? I saw another which had the upper
transmission mount coming apart, and on acceleration, the two metal pieces
of the mount touched each other.