I've lost a good bit of power in my E in the past week or so. It's a 2003 w/t manual transmission. It shifts fine, but it sounds like it takes the engine longer to "rev up" to optimum speed once I shift gears. This seems much worst going uphill. The engine sounds fine, just working harder, because I end up giving it more gas to get around. Could this be a timing chain problem, or possibly just need a tune-up?