Nissan Repair: Problems with a 1987 Nissan Pick-up, throttle position sensor, suttering

Question
I have a 1987 Nissan 4cyl fuel injected pick-up that runs fine when I first start it. After I drive 10 miles or so, or sooner in warmer weather, the engine misses now and then, causing the truck to "stutter". The engine suttering and cutout gets worse as I continue to drive.

I replaced the throttle position sensor, since the stuttering stops if I hit the accelerator. I assumed there was a "dead-spot" in the old throttle sensor, but the replacement of the sensor had no noticeable effect. I assume that once the engine warms up there is something else that is causing the problem. I'd welcome any suggestions on what might cause these symptoms. The truck is old, but only has 109k on it. Still lots of life left in it if I can fix the "stutter".

Answer
Greg,

It is probably the distributor.  Nissan uses an optical pickup to signal the plus to fire.  If the shaft seal in the distributor goes out and they do after 19 years they will get oil on the optics and then when you drive and the engine gets up to temperature the oil works its way up on the shaft until it gets to the shutter wheel.