Possible misfire?

I swear, this car is more moody than I am.

A couple months back we replaced spark plugs, spark plug wires, sway bar linkage, and some other stuff.

A few weeks ago it was over heating, turned out we had to get to housing for the thermostat or whatever the hell it's called replaced. It was "fixed" a year ago by boyfriends uncle, who had to grind down a part to make it fit "correctly". Year later we have to pay $100+ to fix it cause there's a leak and the car was overheating like nobody's business.

Then it started popping/clicking from the front driver side, we had to get it aligned, asked the dude if he could look at it when he was doing the alignment. He saw that the bolt on the sway bar wasn't on completely tight enough. That fixed the clicking/popping noise.

Well - a week or so before the clicking/popping noise started, the thing starts sounding like it's overworking itself on crank-up. The CEL flashed a few times when boyfriend was on his way to work, then it stopped blinking. A week ago it started doing the same. It's been acting like it's not getting enough power, I suppose.

A few days ago the CEL came on and stayed on, after it was blinking a while. So, we went and had the codes ran at the local auto store, it said it was misfiring.

So, we checked the coil pack, it's putting out the correct voltage from what the meter said. Checked one of the sparkplugs, it's good. They're all brand new, wires are new. I read that corrosion on the battery terminal might be causing the misfire, and there was some corrosion on the positive terminal, so we cleaned that off. It didn't act up last night, 'cept about 3 hours later, when the A/C was on, on crank-up.

This morning boyfriend cranked it, and the A/C was turned off, and it didn't act up.

It seems when it sits, with the A/C off, and you crank it, it's fine. But, when you crank it when the A/C is turned on, it does the roughness start-up thing.

I just want to get this fixed. If it's a misfire, which is what the code that came up said it was, then I don't want it to get worse where it's going to mess up something further. We're going off for a couple days in August for my birthday, and then we're going to the beach in September, which is about 300 miles away, and I'm terrified and annoyed. This car just keeps acting like a moody little brat.

if it is related to the ac, it would have to be part of the high idle circuit. if it is acting up and turn turn the ac off, does it level out?

one thing to keep in mind is the coil could be bad and still putting out the correct voltage. I dont personally own a voltmeter that can read the voltage sent by a coil to a spark plug. BUT if you want to test the ignition system do this: take off the appearance covers and etc that hide the wires, and coil pack. wait until it is dark. start the car, and mist water over the wires and coil pack, if you see sparks, or it quits running, then replace what ever you spray. (spray on wire at a time. then the coil pack). do not touch anything in the engine while you do it or you will get shocked.

Ok, on with the ac. IT could be several things. I would immediately jump to the coolant temp sensor since you have had issues with the thermostat. so start with that.

Well, tested the wires, coil pack, and spark plugs. It's all good.

But, it still rumbles right at start-up. The CEL has went off, but the rumbling still happens.

Car isn't running hot, and is running normal temperature.

Could it still be the Coolant Temp Sensor even if it's not running hot, at all?

It doesn't rumble any other time than besides start-up.