Random misfire code and cylinders 1, 2 and 3 codes?

Barely runs at an idle, came up random misfire code and all the spark plugs were pretty much found they had carbon build up on them, like to fuel area ratio was off one of them the whole end was burned off. All that was left was the electrode sticking up, but there was no little arm over the top of it for the spark to bounce in between. I believe that manifold gaskets have been leaking. I had just used some Rislone complete fuel system cleaner designed for GDI engines like mine a couple of days before it happened. Do you think I should change the intake manifold gaskets since it's at 127,000 miles anyway? Also, it only misfires and stuff and like 800 RPMs once I rev it up to about 11 1200 RPMs it smooths right out. And for some reason when I rev it up my computer shows the live data the fuel pressure goes down instead of up it has the high-pressure fuel pump on the fuel rail, and it should range between 500 PSI and 1,600 PSI but when I read mine up it stays around 500 and maybe goes down a little.