My 98 Grand Cherokee has just had the head gasket replaced and now my check engine light is back on and it's still saying that cylinder 1 is misfiring. Has anyone had this problem and what was your solution to fix it?

 

In some cases the piston rings will break, that will cause a miss fire. Now your looking at a big repair job. If that's the case just throw another motor in.

 

check for possible broken or disconnected vacuum line also make sur nethe plug is firing

 

Check the obvious if you have not yet. Is it possible that you cracked a plug or its bad, maybe a plug wire or cap? Injectors plugged in properly? Most of these mentioned components can be swapped from one cylinder to another too. If the miss goes to another cylinder then replace the part that you swapped.

Remove a couple plugs and do a compression test, at least compare #1 with a couple other cylinders.