3rd cylinder misfire. P0303

I have replaced the coil and plug, I had the tools but haven't had the time or experience to compression test. Under acceleration I have a severe misfire and am thinking it's the pos dorman plastic intake. Or possibly a burnt valve, has anyone had this problem or can recommend a cheaper fix than firing a parts cannon. Car ran hearty before it got soaked in a Florida monsoon. I'm at my wits end and need help mechanically and mentally. Also P0446