installed taurus fan; runs hotter on highway (long)

I installed a taurus fan on my 90 gt. I used a 60 amp relay and adjustable thermostat. Anyway the fan cools great while in traffic, but on the highway and when the engine is under load it runs hotter than with the stock clutch fan. I trimmed the shroud of the taurus fan and fitted it in the existing stock shroud. Just wondering if anyone had this problem also. the temp on the gauge reads between M and R on normal now. Things i will be looking into

1. maybe I introduced air into the system when mounting the coolant bottle and runnning the engine with it unattached.
2. the combination of the 2 shrounds cover too much of the radiator.
3. adjusting the fan to come on a little higher to make sure the thermostat stays opened. Maybe the fan comes on too early the thermostat will never open, the water wont circulate and temperture under load will rise?


Thanks

I ported the taurus shroud hoping to get more air into the radiator. I drilled 4 2.5" holes on the part of the shroud where there is room. It didnt help because the temp was still around M or r on the word normal while moving at 45mph. I know the stock gauge isnt accurate, but I know the car was running a lot hotter than with the stock fan.

So i put the fan clutch and guess what, she is running cool again around A on normal in both city and highway driving.

I was only running the electric fan on low, I figured since I live in pittsburgh, PA and dont use the A/C I wouldnt need high. Also the fan cooled great while sitting in traffic.


Couple reasons I think the fan didnt work for me:

the cooling system is stock my radiator is 15 years old and from what I can see it looks pretty corroded. some of the internal tubes are not flowing water from the pass side to the drivers side when the thermostat opens.

I have a aftermarket trans cooler and the Ac evaporter is still there.



Good things about the fan:
It increased horsepower throughout the powerband and reved smoother. I have no proof but honestly it felt similar running a short belt.

I have a 3g alternator and the combination of the fan running, heater on high and headlights did not noticeably draw down the system at idle.

fan was blowing toward the engine

I am going to try and run the fan without the stock shroud. I have to fabricate a mount for the fan and water bottle.