Need some help.

[bbnole]

I have a 1999 miata that I just changed the engine a month ago. My issue is I am getting a p0300 code (Misfire). I find the car hard to start and also when driving it will cut out for a second and then come back on. It seems to happen a 3500 rpms or higher. The tac will just fall to about 3000 rpms and then jump up to where it was before. I think it is the coil pack but dont want to buy the part unless I am sure. Does this seem right?

 

[jmsj578]

You should get on Miata.net for some good discussons on this code. I just did. I found that the P0300 code is most likely the coil pack. It could be a plug, if you're getting P030x codes. There were several threads about this code, there.