Plain Jane OEM nothing to see here rebuild

[JustJeff]

I'm having overheating issues with the engine. I'm using a Taurus efan and Starion thermoswitch in factory location on the back of the water pump housing. Starion switch IIRC is a 195 on and 185 off. I also have a manual on switch wired to cockpit of the car. Fan seems to be working perfectly. I have it wired directly into the main fuselink in the engine compartment on the low setting. I have it setup so that I can swap between to high setting by simply unplugging the low spade terminal and plugging in the high.

Here is what I've noticed so far with normal driving (not driving it hard as I'm still breaking in the engine). Temps will keeping rising and rising and when they start to pass 220 I'll pull the car over and either let it idle with the efan running and hood up or turn off the engine but let the efan run and every so often turn the engine on to cycle what is in the radiator back into the engine.

Here are the contributing factors I've tried to narrow down so far:

1. Put in a new thermostat and while doing that changed to a different used, but working water pump. (It was working fine last time I used it, can mechanical pumps fail?)
2. N/A hood was being used. While I've been driving to avoid boost as much as possible. The Hallman MBC is set to zero boost, but I need to watch how I'm driving. The OEM wastegate simply can't fully bypass. I thought that perhaps because the MBC was not allowing the engine to be in vacuum that it was contributing to heat. By that I mean it may be purging as much of the pressure as it can, it's also trying to keep pressure at zero. That perhaps rather than having vacuum having zero pressure is still pressurized compared to vacuum and thus creates heat. That theory was partially blown out of the water, I put a turbo hood on it yesterday hoping to see lower temps...and did not. (Before it is said, I'm using N/A hood until I get paint work done on the turbo hood and other parts. I keep thinking paint is going to happen and it hasn't yet.)

Other than obvious things where can I start looking for a cure?

1. Flushing radiator and cooling system. Should I flush the heater core seperately?
2. Testing the radiator cap. What pressure cap should a S5 13B T have?
3. Possibly a clogged oil cooler?
4. I have air pump removed and so far only a single belt alt pulley. I had a dual belt pulley with my last alt but usually only used one because of belt slipping. Never had issues with heating.

The engine parts and car did sit for almost a year while the rebuild happened. Is it possible I've got a clogged cooling system or oil cooler? I have both oil and water temp gauges and oil temps seem to be where they should be.