Hey there, Brokenquill. I own a 1984 Toyota Van and I just got a back together last month after replacing the headgasket. The 84s and 85s run the 2.0 Liter 3Y-EC engine. Years 86-89 run the 2.2 Liter 4Y-EC engine which Toyota still uses is Forklifts today. Nice, eh? Anyway. I'll be glad to help you with your problems. There is a sensor around the radiator cap that, if gets unplugged, will cause the "Check Engine" light to turn on and will kill the engine. This is the sensor that, kinda, points towards the valve cover. You might wanna check that out. Hope this helps.
There are also Toyota Van fan sites you can visit.
www.toyotavanpeople.com
www.yotavans.org