Nissan Repair: missfire, phillips screwdriver, nissan 720

Question
I have a 1985 Nissan 720 PU w/2.4z engine. The vehicle has 273k miles on it. It has started to have a missfire while it is warming up and while driving at approx. 55-60 mph. It has never stalled while this is happening. This does not happen everytime the truck is driven. Changed plugs, rotor, cap, wires,and the oxygen sensor (needed them anyway. The old sparkplug tips were dry and covered with a white deposit.  Inside the dist. cap was clean and oil free. I cannot find a cracked vac hose anywhere. Engine parts are original and only uses 1 quart of oil between changes of 3,000 miles.

Answer
Steve,

Did you take the distributor apart to check for oil in the optical pickup?  The distributor is probably the reason the truck is doing what it is.  Take the rotor off and then use a phillips screwdriver to get the center post off and then take the metal cover off and you can get to the optical pickup.