NEED HELP! Codes:P0171, P0174, P0304, Symptoms inside

[taylorRichie]

So I know the codes:
P0171
Fuel Trim System Lean Bank 1
P0174
Fuel Trim System Lean Bank 2
P0304
Misfire on Cylinder 4

It started with just 171, and 174, but 304 came on shortly there after.

I cleaned the MAF and EGR, and replaced the PCV. I then ran seafoam through the gas, and Filled up with Premium. 20 miles on the tank since, and now the CEL is on, and occasionally blinking (assuming that's because of 0304 code)

My vehicle is now idling at 2500RPM!

Advice??

I was planning on Just replacing all my plugs, and hoping for the best, but figure I should post here and get advice before doing anything more.

Should I do Plugs and O2 sensors? Kind of surprised to have issues where my vehicle only has 52,000 miles, and hasn't burned any oil to date.

Thanks for any insight.

Richie