My liberty has started to sputter and lose power. When it gets to 3000 rpm it really, really bogs down. Codeerror code p0300 p0304 p0305. Any ideas

Multiple cylinder misfire...cylinders 4 & 5 for sure. Could be spark plugs, injectors, coil packs...you can switch them around (one thing at a time) to see if the fault follows the part or stays with the cylinder to help narrow down which one is bad.