Lost of power,idles fine, seems to have more power in cooler temps

that is a 12vdc power problem.
the sensors are failing , many do to lost power. (12vdc electrical distribution power)
so use a voltemeter, i bet even at he cig lighter port the voltage drops
below 13.3v running, way below. infact.
are your battery terminals clean,
is the rested voltage at the battery terms 12.6v (keys in pocket)
no? then the battery is being discharged,

Air is more dense at lower temperatures so the cylinders fill better and there is some evidence increased humidity also helps engines to run better.

Replacing stuff in the vague hope it will provide a cure can be expensive and very frustrating and is no substitute for proper checks and replacing only what proves to be faulty.

New plugs won't improve matters if the spark is really weak and a new fuel pump is really money down the drain if the pressure regulator is faulty or the injectors aren't spraying properly or the carb has some blocked jets or if the oxygen sensor is sending the wrong information...

It is best practice to always start with the basics - engine condition, timing, compressions, cylinder leakage and so forth. Your description indicates the engine is short of fuel or fuel that it can use but could equally be caused by a restricted exhaust. I once had a car just like that and it was a worn exhaust cam lobe that was causing the trouble.

hello there
I looks like your oxygen sensor,Try to disconnect and then see what the car does?Let me know.You may need to adjust the fuel mixure,seem it is running a little rich that is why the car in idle goes up and down.
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proporsche

here are the converter symtoms: decreased low rpm power, engine runs a little hotter then normal at cruising speed, exhaust leaks near header, bucking or jerking during accelerating, cats exterior surface temp cooler near outlet. if you suspect the cat of being bad take it to a garage, to find out for sure if it is, have a good day !!

computer and emission controls dont function properly until engine is at running temp. sooooo it may make your car run a little higher trying to warm it up at idle. just depends on car some act real funny about this type of thing. sometimes rpms might be 2000 at idle. it is bad coolant temp sensor. i would fix it.

no your fine, 200F is a fine temprature to run at. If you having no overheating issues just leve it. all my cars run at 190-220F.

does the engine get over heated if so check the radiator system, also check oil level.

try new fan thermostat switch

Hondas are famous for this, my accord does it. This is normal UNLESS it still idles high after normal running temp. has occured. Watch your temp. gauge when it reaches normal temp tap the gas a little bit if the idle drops then it is fine

Just finished fixing my daughters 1999 taurus heat. It would blow warm only when running down the road. At idle it blew cold. I started with replacing thermostat, and water pump because they are the easier fix. Still did not help. Then I replaced the heater core. A daunting job but not that hard to move the dash slighly out of the way to replace. There is a good write up at tarusclub.com. After that, heat was better but at idle, it would still blow cool sometimes. Researched and found answer. Park car on the steepest hill you can find with front of car up. Start car and take off reservoir cap. Let car warm up and keep rpms about 1500. After a while the fluid will come running out of the car and all over the place but it will bring air bubbles with it. Reduce rpm, add more fluid and repeat about 3 times. It will make a mess but after that, the heater works perfectly. We get heat long before the temp gage indicates any and it never blows cold unless you lower the temp.