Pontiac Repair: misfire, water coolant, induction system

Question
I have 2000 gp se with a 3.1 withn 113k I started the car for in the morning and for a few seconds it ran fine an always.Then it started to run rough and the ses light lit.My scan tool showed a p0302.So i changed all plugs and wires.started the engine it still ran rough and still misfire in #2.Then i replaced that coil pack still 302.It had been a few days be fore i could afford the coil,so i thought the #2 plug may be fouled.I pulled it and it was.I cleaned it but no better.I then repaced the #2 plug.Still code p0302.The engine is running better and the ses light is flaching all the time. Thank you for any help.vince

Answer
Hi
I would, if you feel conifedent it is no longer the ignition system, look at the fuel and induction system next, and finally engine mechanical.
Injector fo #2 cyl. Injector harness. Was the liquid on plug fuel or water/coolant? It MAY be that you have a lower intake gasket seeping coolant into that #2 cylinder.
MAybe have the injectors power flushed. They can also be checked for proper flow rates.
If all this is checked out, and found OK, the only other misfire causing item can be engine mechanical (valve, valve spring, piston, etc....) which you may run a compression test on that cyl.
BTW do not drive it too long with flashing SES, as that is a Catalyst Damaging condition.
Hope this helps.
Good luck
PAwl