Would suggest running a quart or two of automatic transmission fluid in your engine for a couple of hundred miles...then change oil and filters...this oil is very heavily laden with detergent compounds and will help clean out sludge/varnish that may have accumulated while sitting...very common problem..also attacks fuel dist., fuel pumps, fuel filters etc etc...so you rough running might be related to dirty fuel systems, and the blow by to stuck sealing rings on the piston. Dried out valve stem seals might allow this if your exhaust is restricted as mentioned...no blue exhaust smoke is also a good sign as normally excessive blow by will result in burning oil and visible signs thereof.
Also check the valve cover vent valve which should be found in the breather hose that goes from the valve cover to the air filter housing...not sure where it is located on the 8V's, but it should be in that breather hose assembly. A plugged vent will force all excessive valve cover gasses out the oil fill port instead of into the filter box.