Had one a few years older. I think the spline was weaker on the transmission in 2003+. The transmissions for the 3rd gen was worse, you have a 4th gen. That's why rockauto sells a torque converter for around $100. Mine had over 200, around 220k I think before I got rid of it. Mine had the regular green coolant. Replaced the coolant tank once and it was fine afterwards. You only do that if you get a low coolant warning and it's full. When they do go, I'm told they typically just blow the head gasket. As for the spark plugs, you don't have to do the manifold, if you take off the covers for the cabin filter, you can squeeze in there. But the intake manifolds gaskets are also known to leak so if you do it, you should also do the PCV while you've got it off and just use the Motorcraft plugs. DPFE also used to go, don't fall for replacing the EGR when that code comes up. As for the hoses, yeah the rear hose tends to rust out. Also there's a custom hose with the thermostat as one unit so that's also good to replace. Same with the belts and don't forget the water pump. I used 5w20 all the time but threw in 5w30 when it was on sale. Seemed fine on either. The oil pan gasket tends to leak so if it doesn't I'd just use 5w20, I noticed it didn't leak as much with 5w30. You had to drop the exhaust in order to change the oil pan so I never bothered.
I probably put close to 200k on the car as I bought it used. Changed lots of stuff over the years, tie rods, sway bar links, motor mounts, front/rear struts, CV joints, front/rear brakes (just get a rear brake drum kit with all the parts when doing the rears), brake light switch, flex pipe/muffler, alternator, etc. Mine was an SEL so I had the climate control with the cassette deck. If you don't have it, you can grab them on eBay for about $50 and use a cassette adapter to play music from your phone.
Taurusclub.com is a good forum for that car. They made so many of those cars that at least the parts are cheap.
