My husband has a '95 Dodge Ram 1500. During the last snow he took it for a "spin". Afterwards it ran really rough. It idles really rough and acts like it's going to cut off. The RPM needle is bouncing from 1000 to 1200 then drops to about 500 and back up again. No backfiring yet! Checked the plugs and all are firing. Did the dollar bill test in the exhaust and sure enough it flapped in both directions. All I remember about that test was burnt valves or the timing is off. It has a timing chain and I can't find anything about setting the timing. I know you can set the timing on a belt, but what about a timing chain. It has a 5.9L engine. Could it be that during my husbands joy ride he could have caused a vaccum leak by knocking off a hose while plowing over huge snow mounds.Any advice or specs would be appreciated.