I have a 99 Boxster 2.5L with 150,000 (IMS bearing upgrade already done). It misfires on the passanger side. P001 p002 p003 are the codes I am getting. Also, if I hold the throttle for a second or two, past 1200 rpm, I get this loud rattle/ clatter noise. NOT rod knock but maybe a few bad lifters? It won't do it if I blip the throttle, but only when I hold it. Here are a list of things I have replaced to try and fix the misfiring
I didn't find the right solution from the Internet.
References:
https://www.pca.org/tech/engine-misfire-all-bank-1-cylinders-lifter-rattle
Explainer Video Example