I've got a few questions regarding your engine running hot:
1) How are you determining that it's running hot? (Factory gauges are notoriously inaccurate, and the only way to get an honest temp reading is with an aftermarket gauge)
2) Does it ever "boil over"? (this is a sign of a weak radiator cap. a Stant pressure relief cap, with a red lever, rated at 16 psi, would be a good replacement)
3) When you said you "dropped in an 80/20 antifreeze mix", you did mean 80% water/20% coolant, right? (coolant actually retains heat, and a mixture containing more than 20% coolant will actually cause the system to run hotter)
4) Do you have the factory fan shroud installed?
Installing the 180 t-stat will certainly help, but I would have gone with an OEM 192 from Ford.
As far as your cats being clogged, this is easily checked with a vacuum gauge. There are two easy tests you can run to determine if your exhaust is restricted (cats clogged).
First test:
1) Attach vacuum gauge to manifold vacuum source.
2) Observe vacuum at idle.
3) Snap throttle to WOT and release, while watching the gauge.
The vacuum gauge should drop to almost zero when you hit WOT. When the throttle snaps closed immediately after, the vacuum should read 4" to 6" higher than what it did at idle. It should then settle back at the same reading it was at idle before the WOT snap. This whole exchange should go from idle reading to idle reading in 2-3 seconds, tops. If it takes longer for the gauge to return to the same idle reading, your exhaust is restricted. The longer it takes, the worse the restriction.
Second test:
1) Attach vacuum gauge to manifold vacuum source.
2) Warm up engine.
3) Observe vacuum at idle.
4) Leave engine idling for 10 minutes. Do not touch anything on the car during this time. In fact, go inside and fix some coffee.
5) After 10 minutes, observe the vacuum.
If the vacuum is the same or higher, you don't have any resctrictions. If the vacuum gauge has dropped, you do have a restriction. The more it drops, the greater the restriction. If it drops 1" or more, you have a serious restriction. 2" or more and you might as well have the exhaust welded shut. Keep in mind that a rich exhaust will clog up cats in a hurry.
Take care,
-Chris
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