I have a 2008 chevy express 2500 4.8L. I keep getting P0308 codes. I have changed the #8 coil 3 times. Have changed the MAF sensor, throttle sensor and anything else that is giving me a rough idle etc. Has anyone else had this kind of problem and what did you do to correct it so your van runs good??? Thanks
Jeff

 

Did you change the spark plug? Do a compression check on #8 and make sure the injector is working correctly.

 

I changed the plugs last year about 1200 miles. no on compression test. and no on injector test

 

The culprit is either spark or fuel. If you've ensured there's good spark then the next step is to check for a fuel issue. On a 2008 you should be able to access the injectors, you could try swapping #8 with another one and see if the misfire code moves with it, assuming it's not obviously dirty or clogged when it comes out.

Big Al's Bike & Auto on Youtube just changed an injector in a 2006 pickup because of misfire codes, the truck had sat a couple years and bad fuel clogged one up good.