what do you guyz think of converting my 90 tracker over to a heated O2 sensor?

I shouldn't think its worth it. The ECU won't know its heated so it would still only take readings based on its current programming. I'm surprised its not heated anyway, my 8V is although I know from what Wild has previously posted the 89s differ a fair bit, anyone know the changeover year?

I looked at an 89 and under the TB there was some sort of metering sensor that my 90 doesn't have.

a heated O2 is an oxygen sensor, with a little heater in it. the ECM will not need any programming it is just more accurate! and efficent

There is a heater under the throttle body for cold climates. I do know what a heated O2 sensor is. The problem is that the sensor is inaccurate unless it is at the correct temperature. The ECU doesn't know what temperature it is at so it is programmed to switch to closed loop only under certain conditions. The ECU runs open loop under the following conditions:

At engine start and while after start enrichments are applied
When engine coolant temperature is low
Under heavy loads, i.e. hard acceleration or wide open throttle
When fuel is shut off, i.e. during decceleration
When oxygen sensor is cold

Now if it expects the O2 sensor to be unheated it will be programmed with narrower thresholds, particularly at low RPM and lower coolant temperatures. The stock ECU can't be reprogrammed, I built my own replacement circuit board so I can make it do whatever i want 

my 90 doesn't have that heater, I saw one on an 89. am I suppost to have one?

I removed mine, you know how cold it gets here in Cal
 
That thing is called the PTC heater
(positive temperature coefficient)
it's a cold weather, and more specifically
a cold start help, tho I never had trouble
starting in the mountains at say 20*, so
it's more likley a thing you don't want, it
would help cold start drivability, instead
of warming your engine first

Wild