95 E320 Cruise Control Works Sometimes

[IYAAYAS]

I've been having this issue for a couple years now and, well, it's time to get this fixed (getting sick of it)!
I noticed that most of the time where my cruise won't set is when it is about 70*F or higher outside. Is the relay located under the hood? If so, could it be that the relay switch is overheating from the engine temp + the outside temp?

Not related to this issue... I recently noticed that my exhaust resonator is badly rusted to where (from what it looks like) the first layer of metal is flaking off. Instead of replacing the $166 resonator - ********.com -, would it hurt anything if I just cut the damn thing off and ran an exhaust pipe instead?

Thanks for your advice!