I will try to keep this as brief as possible. 87 Vanagon, stock 2.1. intermittent rough run and loss of pwr. So far, have tested with good parts ECM, AFM, Dist, plugs, plug wires, alternator, coil, fuel pressure/flow rate, idle stabilizer, cold temp sensor, good fuel, fuel filter, fuel pump, fuel injectors, O2 sensor, ohm'ed wires to and from all components. Have done wiggle test on as many wires as we can get to or think of. Checked for vacuum leaks. When running good, very smooth idle, warm-up cycle, acceleration, etc . Never had one run better in my 25 yrs of owning one. Just had about 6 days of 300 plus miles of driving without a hitch. When rough, sometimes can be smooth for first 5-10 secs, then problems surface. Most of time, when rough, rough from very beginning. Have worked alongside a mechanic who has worked vanagons since the 80's, but we are both stumped. Could use any and all  ideas/suggestions. Or someone to suggest in this region of the country. Steven Mills,  Oklahoma