first off, never ever run without an air filter. the filter being super saturated in oil is a possibility. if the engine cant breathe its not goind to make power. also that oil could have clogged up your IAC and coated up your throttle body a bit. clean the filter with one of those k&n service kits and re-oil it. clean the throttle body and IAC. Also gm has a tsb dealing with K&N and other aftermarket filters that use oil. In the tsb it says the filter oil can get into the MAP sensor and cause some problems. Speed density engines are heavily reliant on the MAP. Also bosch plugs have probably the worst plug side electrode setup of any plug ive seen. last winter i could have filled a 5gallon bucket with all the new and old bosch plugs i changed out with another type of plug due to fuel fouling and hard starting. the electrode is very small, about the size of the lead that you use in a mechanical pencil. All it takes is a drop of fuel on the electrode to foul it out. changing the coils isnt as bad as you would think. going from underneath on the passenger side or going through the passenger wheel well with the tire removed it isnt too bad. long 1/4drive extensions and a universal swivel make a lot of difference too.