Wow, so many responses to my post. Thank you so much! I'm a relatively low time pilot (138 hours PIC) so all of this is still very much a learning experience for me, albeit one without a CFI in my ear yelling to use more rudder lol.
Some clarifying information that were asked throughout this threat.
Weather conditions were cold as hell (-17F) but perfectly VFR, sunny with 30 kts headwind aloft but only about 5 kts of wind on the ground.
Terrain was flat with little to no trees but every field had a few feet of soft powder snow. I was loosely following a major highway I would have been within gliding distance of at all times.
No other airports besides the one I'm now stuck at for an hour either way. It's VERY rural out here.
Departure airport was not my home airport. My home airport is five hours from here. We were on our way home.
Airplane is new to me so not 100% familiar with the airplane just yet. I mean, I am in terms of flying it, but you know what I mean, I don't know the plane like the back of my hand, or like I did with my last plane which I've flown for nearly 100 hours. I've only flown the Cherokee for about 10 hours since I bought it last month.
I was 90% certain it's just an instrument issue and nothing wrong with the engine. Originally, I was setting up for a landing right besides the highway in a field but I played around with the power settings and the engine responded as expected based on engine sound. Based on that, I decided to not go down in a field but instead head to the airport that was nearby. I think the one thing that startled me the most was the strange grinding sound I heard. Without it, I might have continued flight to a more suitable airport I guess. Hard to tell sitting on a sofa indoors though.
Update about the situation.
I found a mechanic who works on ag planes here during the winter and he looked at it today. The tach cable is shot beyond repair. We ordered a new one which should have arrived same day via courier but it didn't so we're stuck for another night at least. Apparently the tach itself is also on its last leg so once home I'll change that as well. My local mechanic has a tach sitting around that fits the Cherokee.
Well, another crazy aviation story to tell I guess. I like the boring stories that go like "well, we took off, and landed at our destination three hours later..." much better than the crazy ones.
To everyone from further south: Yes, -17F is really cold, inhumanely cold and it should be illegal for anyone to live in climates that cold. This entire region should just be evacuated from November until March. We'll voluntarily evacuate next month and head down to Florida for a little while. Hopefully all my flying stories flying to Florida and then back north a few weeks later will be of the boring kind.
Sounds like you're taking it in stride. I'm sure someone will be along to say "time to spare go by air" and all that but trust me that flights like this are in the minority. But just in case, hotel and rental car status points are handy to have sometimes.
