ClubLexus - Lexus Forum Discussion - ticking sound bent or stuck valve?

I have P0308 code.
I have changed spark plug,plug wires,both coil pack, both coil pack connectors,fuel injector is perfect.
My problem is constant tapping noise from exhaust on the passenger side.
Checked with scope no tapping noise from bottom or valve cover.
Engine will misfire only on cylinder #8. The noise i here almost sounds like its under the car on passenger side. No i have not done a compression test yet. Dont yell at me LOL! I am thinking this might be a bent valve or maybe a stuck valve. I did read some post i should try and clean it with carb cleaner. Any help i am lost and i just had timing belt water pump serviced 7 months ago. Car was running flawlessly.