can I ask, when did this problem start? You said it was running rough before the tune up. Did the tune up make it worse? Do thos 318's have a heat raiser off the exhaust manifold? Is it on the drivers side? Could the "flap" be stuck shut? this would cause the exhaust not to be able to flow, maybe creating some back-pressure issues?
They only other ting would be you have broken valve train problems only on the drivers side, that would be highly unlikely, or it would be unlikely that each cylinder would be effected.
So that brings it back to fuel and spark.


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Coming soon!!!!