Hi all. I am new here...not to blazers....I have a problem with my 2000 blazer. Last spring i got the code po300 random multiple misfires. I did a tune up...ran great for 3 months....started acting up again. Then I changed coil pack and EGR. Ran great for a couple days then back to the same routine. After it rains or is humid it hard starts....usually have to jump it to turn it over it takes that long. However this last time....it will not fire. The battery is good....I hear the fuel pump....Going to test pressure and change filter...but i didnt think it acted like a pump....seems more like lack of spark to plugs. I have good spark off coil....weak spark off of distributor.....any advice peeps.....really effing puzzled right now.