So I have a 98 Ford Ranger manual transmission, and I've encountered a problem that has just started today. I got my oil change done, and as soon as I got on the road again(a professional place did it), my truck will keep the RPMs up. This lasts for a couple seconds or several, hitting no higher than 3k RPM once I've either popped the gear out or used the clutch to shift into neutral. Furthermore, when I come to an idle, it is now idling at around 800 RPM and is getting a bad shake. Typically, my truck idles around 1200 RPM. Is this a serious problem that if unlooked will get worse, or is it something I can forgo for a bit? I'm leaving on a 1,200 mile trip this Saturday and I don't want something to break on the way there. Thanks for looking!