Hmm...I think the problem is simpler than how you see it.
CF1 and CF2 can be retrofitted without major problems, so I don't think this is the reason of the issues you face, only the head gasket varies in thickness(My99 has more CR)
Me think that you instrument cluster doesn't match with the temp sensor fitted to the engine, has your's the chrome rings around the gauges?
Your thermostat should open at 83șC (both versions works at 83șC) and looks like you have the correct temp sensor by looking at the pics you provided, so all this is okay.
Then, if all above is correct, then you can start looking into cooling issues. Best is to get a diagnostic tool to compare temp readings ECU vs Instrument cluster, check 1st and 2nd speeds of radiator fan and so on..on open roads, engine temp should be near the opening temp of the thermostat, even if you trash it, if it goes up when asking for power, you radiator is internally clogged (usual). The thing is that you say you have most problems on slow, city driving..what's the ambient temp out there?
Powered by Invision Power Board (http://www.invisionboard.com)
© Invision Power Services (http://www.invisionpower.com)