Multiple random misfires - 01 zr2
 

2001 zr2, 6 inch all suspension lift and 33/12.5/15s.
My blazer is misfiring when its cold but not at idle when i start it up. its after i start to drive and after about 2-3 minutes of driving it smoothes out. i did plugs, wires, cap and rotor about 2 weeks ago and this problem started just yesterday. CEL is on and was blinking today on my way to work. CEL has been on since i bought it about a month ago, only blinked at me before when i tried to drive faster than 70mph. Didnt wanna go any faster at all and the rpms stuck right at about 3000 with it pinned to the floor. I will keep updating as i go and learn/try new things. If you have ANY suggestions or input PLEASE share. Thanks.

Got my CEL codes today and they are..
P0300- Random Misfire
P0101- MAP/MAF/VAF sensor
P0452- Fuel tank pressure sensor (evap emission system)
P0404- EGR system fault

Im going to start with trying to clean up the mass airflow sensor

Died completely today. right in front of my house as i was pulling away. It started up fine and then drove crappy about half way to the auto parts store. could this be a fuel problem? im thinking its got to be more than just the mass airflow sensor. i cleaned it but i have to let the engine cool down before i can see if it did anything or not.

I also noticed that before i this problem even started my idle would bounce back and forth between about 700 and 800 rpms (didnt think much of it) and now its lower around 500 and 600 but seems to be steady now. I dont know what this means but im hoping to give as much information that i can so that get some help on this.

I'm not the expert advice you need, but I just got some help for my case posted in the 2nd Gen S section with the same first two codes you have. The recommendation was to do a fuel pressure and leakdown test. Apparently you can get a loaned tester from Autozone and the directions for the test are posted in several places on the forum in addition to my thread.

I got the fuel pressure tester last night and it seemed alright and i cleaned my MAF sensor. I did notice last night that the hose/tube from the valve cover was not on the air intake, just resting next to it and its on the backside so i must have not noticed it off. Could that cause these kind of symptoms? I put it back on last night and let it cool down over night and seemed to make a difference but it was alot warmer outside today so im not sure.