alright so i have a 99 1500 with a 318 and its having a misfire issue even tho i have put on a brand new cap,rotor,wires,plugs and coil on it any suggestions on why it might still be a misfire.

 

Try this:

http://dodgeram.info/tsb/1998/18-48-98/18-48-98-v8.htm

 

do you know which cylinder is misfiring? you could have a plugged or not working injector. you could also have low compression on a cylinder. You could do a cylinder compression test and if there is low compression on a cylinder then do a cylinder leakdown test. how many miles do you have on your truck?

 

I also forgot to mention that if you didn't fix your plenum that may be the cause.

 

+1...... At least read the sticky and check it.