Always diagnose in order of cheapest repair to most expensive if you can't pinpoint the actual issue (i.e. no error code to read from the ECU)
cold misfires are typically the result of:
- Hydraulic Lifers gummed up when cold.
- CCV (crank case valve---sometimes called a PCV)
- Sparkplugs gummed up, work only when warm.
- Oil leaking into sparkplug chamber (valve cover gasket needs replacing) - typically flashes the check engine light when the misfire happens.
- Coil Packs
- Wiring Harness for Coil Packs
Most of these issues will throw an ECU code that can be read by a scanner, typically a P134X code. If you get a Check Engine Light then the fuel would be cut-off from the cylinder that experienced the misfire. Turning off the engine and turning it back on would reactive the cylinder.
So again, cheapest solutions first!
A bottle of Wynn's Hydraulic Lifter cleaner to ungum them, has been used successfully on our engines many times. Some people like Seafoam too. Take your pick.
Next up would be the spark plugs. Remove your coil packs, check the plugs for any oil residue on them - replace.
If you've got oil in there, then you'll need to replace your valve cover gasket.
Put it all back together, check for misfires. If you have a misfire then put on some thick gloves. Leave the engine idiling and listen closely to the spark plug coil packs... you're listening for a loud 'spark' sound, like an electric BBQ lighter. If you hear it, then one of your coils are toast. Alternately you can touch them WITH A RUBBER GLOVED HAND lightly. If one of them is toast then it will be VERY hot to the touch. The others would be hot, but one (or more) would be sizzling hot. And the safest way to check them to to hook them up to an ammeter and check the resistance in them---though it's not always 100% accurate.
If you've still got issues when I would look at the CCV.
