I'd never put new plugs in and do a seafoam treatment thru the intake. It "could" cause the brand new plugs to fowl. Now if adding a fuel treatment to your tank gives you issues you've got other problems.
The 3.7L is an inline engine and they'll always run rougher (vibration wise) vs say a V8. Just two totally different setups. Easy to see the difference in a 3.7L vs a 5.3L. From broken motor mounts to torn up manifolds. Inline engines vibrate more.
I read a few threads and they never clarified if they had bad coils, boots, the wrong plug, wet coilpacks from a leaking hood louver, or the dreaded head issue related to misfires. Very very very easy to get the wrong boxed plug or completely wrong part from the kid behind the counter.
So far I guess I'm a rebel lol. I've used pretty much everything on my H3's that hasn't been OEM, like brake pads, rotors, oil sending unit, variable valve timing sensor, waterpump, thermostat, fan clutch, idler pulley, spark plugs, CV Axles, spark plug boots (5.3L), silla radiator, transmission filter/gasket, and a K&N air filter (with a prefilter). My H3's run great, zero issues and honestly after my initial tune up's after buying them I haven't spent any time under the hood except for a 10min oil change.
Nothing wrong with OEM stuff, but plenty of aftetmarket name brands work just as well if not better.