Random Misfire/Fuel Drop/Bogging down HELP PLZ

[BNaylor]

To start you should be using the OEM AC Delco double platinum or iridiums if you are stock. The copper core is used when you have supercharger mods like a smaller SC pulley to help control knock retard caused by detonation.

From your description of the spark plug it doesn't sound like they are being burned up. Are all spark plugs from all cylinders the same? I'd be more worried if the ceramic stayed white after a few months of operation. Light brown can be normal. Do you have any knowledge on how to read spark plugs? How does yours look compared to this one? This one is normal. In addition to ignition issues random misfires can be caused by a fuel injection system problem or even an internal engine problem depending on your mileage.

[davel68]

Sounds to me that the map sensor could be at fault or low vacuum pressure to the map sensor.With that many miles on the engine I would first check the vacuum to the map sensor with a vacuum gage.You should have anywhere from 18 to 21"hg of vacuum at idle with a warm engine.Anything below 15"hg would indicate worn rings,plugged exhaust system which you already had checked,or late timing which is controlled by ther computer.When you pull the vacuum hose to the map sensor watch the exhaust pipe and you should start to see it go very rich with black smoke coming out and then when plug the vacuum hose back to the map sensor it should lean back out.If this is happening then the map sensor is probably ok.I know this isn't much but maybe it will help.