How to pin point misfiring cause. .. on 1997 Pontiac Grand Prix GTP

P0300 and p0301 keep popping up and my engine shakes bad at 10 or less mph I have changed spark plugs and wires no help im not sure if my ignition controller is bad or what it just happend last week I even changed the egr and thermastat no clue and I dont think vacuum leak. .. any ideas. ..

by in Wilsonville, OR on May 07, 2013
1 answer
ANSWER by on May 07, 2013
GET PROPER DIAG IT COULD BE COIL ISSUE
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