Uhhh there are better ways to find a cold cylinder than touching a exhaust pipe. One involves....wait...for ..it..... a ....spray bottle! Or just get ya a digi temp reader thing.
But yea im with blink and then whoever else mentioned bad coils. Sparks are cheap enough that i would never clean one, just throw it away and buy a new one. Its either your fuel pump taking a shit, bad coil(s) or possibly clogged injector(s) or pinched fuel line. If No to all of these then yes start chasing electrical gremlins and cleaning contact connections.
*Official winner of one Riflemans 1/5 insert