so I got a diagnostic...
 

... and I got an EGR and TPS malfunction. However, I can't link that to the symptoms. When cold, my 87 NA idles unstable but ONLY after I start driving. After its been warmed up, it runs fine. After I've been driving for a while the idle speed goes up to about 1200 RPM. Also, the check engine light comes on only after I drive the car at about 50 mph or more.

I'd like to see what you guys think before I pay for a full inspection. In the meantime, I'll look around for parts (OEM, as Im presuming there are no aftermarket ones). Help appreciated.

did you do a diag and get error codes ?

My turbo89 automatically high idles whenever it gets worried that its getting hot, then it goes back to low idle... dunno if that helps. when you say idles unstable can you give a little better description? Is it all over the place? IS it high low high low. Does it sag cough sputter almost die then back to normal, it'll halep diagnose if you can give a bit more info. Does the check engine come on as you rev through each gear or only at 50? Are you sure it doesn't come on at 40? Changed all your filters and oil lately right?

Yeah I got error codes 51 TPS IDLE SWITCH CONTACTS OPEN and 71 EGR SYSTEM PROBLEM.

As far as my idling, after its been running for a while, it will idle at 1200-1300 RPM. But, until its been turned off for ahile it wont go down. When its cold, it will idle low, and as I start driving and put the clutch in, it will idle way down low and spudder, go up and down. Sometimes it will stall. But, as it warms up it stops. the check engine only comes on at high revs or high speeds, but not with normal city driving.

Ok well the Throttle Position Sensor sounds like your idle problem, and as for the EGR problem, thats most likely where your high rev check like is coming from, high revs brings Vacuum manifold pressure down and one of the check valves or recircvalves may be getting ready to take a dump or is curently dumping on you... If you've got a multimeter you can probably DC the TPS and test it directly. As for the EGR system... buy a mighty vac hand pump and a snickers.