Need some basic knowledge on exhaust/engine issue

Hello, all hopefully someone here may know the issue. I have an xj6 1997 base model. I started the engine up to warm up, was fine one minute but than while idle it started to sound funny I looked and it was running rough and the exhaust seemed to be puffing slower rougher puffs. Any ideas where to start looking and what may be the issue.

Ignition coils failing?