My friend has a 2004 Volvo S40 T5 that shakes really bad at idle, particularly while idling in gear with the foot on the brake. (He bought it in this condition dirt cheap, everything else is perfect on it.)

We checked the timing, and the plugs and all the simple stuff we could think of. So he took it to a shop that deals with Volvos and they gave him a diognosis of what was wrong with it and said that they CAN fix it. Ofcourse they didn't.

They replaced the cam gears, cam position sensor, switched the cams to their proper position (someone swaped them around before), replaced leaky water pump and a couple other things I can't remember.

After all this, the car still isn't right and continues shaking at idle. The mechanic also said that there is a bent valve (caused by the timing/cams being wrong). Could the bent valve be the real cause to the issue?

But we then ran a compression test on the engine and all 5 cylinders were consistant in the 120-130 PSI range and did not leak down, this seemed to rule out a bent valve to us, but not 100% sure still. Is 120-130 PSI still low for this engine?

Or could it be something like a loose/bad vacuum line?

Any other suggestions as to what would be the problem?

Sorry for the long post, but I'm trying to help out a good friend so any help will be much appreciated. Thank you.