st141 corona running crapola

[metallibanger05]

hey all, corona has the 2s motor, was driving good down the highway and then it suddenly started running bad like it droped a cyl, replaced plugs and leads and its still running bad, checked fuel and is all good, checked all plugs for spark and the 4th is only sparking the tinyest bit, checked and cleaned dizzy cap and is all good but still no different, is it easy to swap dizzys, or could it be another problem like intake manifold? any feedback will be awesome, cheers

[metallibanger05]

ok swapped the dizzy and no better, must be a fuel issue, maybe valves? i checked intake and seems all good?

[CELICASUPRA7M]

I'd give it a compression test to rule out mechanical probs