Here's one for ya 2001 blazer 4 door 4wd throwing codes p0300 p0102 p0452
 

Ok It chuges if your light on the gas or going up hills it hates going 40 or under I've checked plugs ,wires ,dis ,vacuum ,lines ,coolent , air filters evap canister, I also had the slow pumping problem untill i zip ties the vapor canister together its the thing under the spare. I need help please

start with the P0102. https://blazerforum.com/forum/diagno...plained-28157/

I have checked maf its good I think I have it because I took it off a few days ago I'm replacing the valve under spare. Lots of rust but all the hoses look,great

Then you need to clear the codes and make sure what is currently the problem and what is not. ps - anything P0452 related is not going to cause a misfire and P0300 is a result of a problem, not a cause.