My check engine light came on last week and I had the trouble codes pulled and they gave me 3 codes.
P0301- cylinder 1 misfire
P0300- random cylinder misfire
P0400- (I think) EGR flow malfunction
I'm not positive but when I changed the oil last time I had a vacume line come off from somewhere. And I couldn't find where it came from. But after seeing the EGR code I think that it may have came off the EGR valve or a sensor that attaches to it.
My question is, could a vacume line cause this trouble code?

As for the first 2 codes, I thought I should start at cylinder #1 and replace the plugs, and check the wires and if that didn't fix the problem I would see if I could get the coil tested.
Can anyone tell me if I'm on the right track or if I should be going in another direction.
Thanks