In my 2005 subaru forester (boxer 4 engine), I get grinding noise when I accelerate the car and the engine sped through 1750 to 2000 rpm. The noise is more pronounced when the engine is cold. the noise is rarely heard after the engine has fully warmed up. with the windows down, the noise appears to come from below the car. The noise is rarely heard when the car is in parking and the engine is reved . cna you please help?

SOURCE: Subaru Outback - '03 boxer 2.5L engine sounds like a diesel

heavier oil if you are not in a cold climate. but before you do that have the oil pressure checked. We used to use a can of STP every once in a while on a motor in a dodge we had... nothing wrong with it... was just noisy.

Robert

SOURCE: subaru forester heater

take back to the dealer,hopefully the will find that the blend door cable is off or not adjusted properly

SOURCE: Subaru Forester 1999 GLS spark plug gap?

spark plug make= ngk
plug type =BKR6E-11
GAP=1.1mm A TURBO MODEL WILL BE 0.7-0.8 MM GAP

SOURCE: 2002 Subaru Forester with grinding noise and

Sounds like the differential to me, when the power drops you are probably crunching a broken piece thru the ring and pinion gears. This can be very dangerous, could lock the back wheels up while you are driving down the road and get you or someone else killed.

SOURCE: 2000 subaru forester ignition coil wiring

Are there any other possible problems, or you are just not receiving spark at all now?

The coilpack could be dead and just need replaced. If you have a voltmeter or a test light, check the wiring on both sides of the coilpack harness to make sure it is receiving power.
I don't believe Subaru used ignitors past '99, but if they did, your should be located on the firewall behind the throttle body. Make sure it's plugged in and receiving power.

Coil packs do go bad from time to time. I had to replace mine in my
'98 Impreza a while back.

Goodluck!