check your spark plug wires, distributor cap, points, etc., anything related to timing.

 

maybe the spark plug itself???

do you have points in your distributor? I'd say get a new condensor and points, gap them properly.

 

I may be wrong but the timing light would still blink even if the spark plug wasn't firing. It must be something before the the wire that is causing it to lose charge.

 

If the spark plug isn't grounding to the head at higher rpms, I suppose the wire wouldn't have a complete circuit and therefore the signal may not go through.

The cap or points does seem more likely to cause the problem though.

 

lol, that's why I recommended points and such.

 

I was having a sorta similar problem with #2&3 on my car. The plug would spark but the cylinders were not always working. Problem was my injectors were not always opening. The little electrical plug that turns the injectors on and off was corroded and were not working, so i put on new ones and that fixed the problem. you may want to check those.