99xj has missfire on 3&4 cylinders. Just replaced plugs wires cap and rotor and did not help. Sprayed intake and vacume hoses with carb cleaner and did not change idel. What else should I check?

 

Compression

 

x2 could be a blown head gasket between 3 and 4.

 

My buddy had the same problem with his and his head gasket was bad. Had a mis in #1 & #3 cylinder.

 

Compression is 30 psi on 3&4. I think it is a head gasket or the head.

 

I would say just gasket, considering you have a distributor (I would think cuz you said you changed the cap and rotor), which means you probably have the 0630 head which is pretty solid. In late 99 they started to use the 0331 head which is prone to cracking, but I believe those all had the coil packs instead of the distributor. Not that it's impossible for the 0630 to crack, just alot less likely.

 

compression check then change the head gasket.

 

Thanks, I am going to replace the head gasket now.