the steering in my suburban is too soft - it works but there is no resistance against my turning the wheel. the dealer told me the EVO valve likely needs to be replaced.

Is this something one can do themselves? IF so, any suggestions on instructions would certainly be helpful.

Thanks in advance for any help...

EVO valve?I'm guessing,does it have to do with the power steering pump pressure output?If so, the valve could be stuck and not varying the pump pressure as required.You have full pump pressure all the time making the turning of the steering wheel effortless.If this is the culprit,removal of the power steering pump is required and then remove the valve.I hope this helps
chuck's

Check the forum 99 suburban steering problem.EVO has been referred to as the steering wheel position sensor.
chuck's