i have 2 problems i need help fixing.
98 blazer, 4.3 v6, 3.73 ratio, 2 dr, 4x4, 127777 miles

problem 1) p0300 code (random misfire) i have changed coil, cap, roter, plugs, wires and fuel filter. it is still hitting, is there anything else that could cause it. i have done everything the guys at auto zone know to do. SES turns on around 60 mph, will turn off when going city speeds for a day or so. first hit day after put fuel sys cleaner in. been getting poor milage.


problem 2) 4 wd not working. made a lot of clicking sounds when it went out. transfer case locks in. (cant spin drive shaft when 4wd engaged, can when not engaged) something in front axle i figure. was interstate driving in 2wd when it went out.

 

This may help you with your misfire codes.
https://blazerforum.com/forum/diagnostic-trouble-codes-dtcs-49/p030x-explained-x%3D0-1-2-3-4-5-6-a-35153/

 

the ses light went out on a long trip on friday and has not returned on again. 2 overnight cool downs, high speeds (75+) and long driving.

how about the 4x4 not working.

 

For your 4WD problem, check out this post, it gives a great run down of your problem and how to fix it and basically why it occurs

https://blazerforum.com/forum/tech-articles-diy-29/4x4-no-worky-maybe-will-help-7180/