Fuel or Ignition Transistor 280zxt

When cold car misses. When fully warm sounds like 1 cylinder misses but runs ok. (have changed plugs). On a warm day and travling more than 40 min going interstate speed suddenly speed falls off and giving gas does not immediately do much good after 10-20 seconds it clears up and runs fine 3-4 min then it repeats this pattern.

Do I look for a clogged fuel line or should the first suspect be the ignition transistor by the coil heating up?

I have changed the main fuel filter 3-4 months back. I have not checked the fuel pump but initial fuel pressure seems fine at around 32psi.