Cleaning throttle position sensor on 87 TR?

If you break the outer case apart, you could clean the contacts used for the WOT switch, but the idle position switch is another sealed switch inside the throttle microswitch so you'd have to break that open too to reach its contacts for cleaning (and then seal everything back up).

Not worth the time hassle or potential unreliabilty -- better to just buy a new one from a Bosch supplier (e.g., www.importeccatalog.com) using the Bosch 10-digit PN of 0280120310 for ~$65 if the idle switch portion isn't working well IMO. This is an excellent photo of the internals posted by someone else from their 328 (328 and TR use the same throttle microswitch):
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On a US TR (KE-Jet with Lambda), when the idle portion of the switch is closed, it puts a voltage onto one of the injection ecu pins which "tells" the injection ecus to not try use the O2 sensor output so quickly/absolutely -- i.e., when you're at high RPM with a closed throttle and the RPM is falling (e.g., you were traveling at a constant speed but have now lifted off to come to a stop), it prevents the fuel delivery from going super-low so it won't stumble badly when it does reach ~1000 RPM; and, when at idle RPM with a closed throttle, it tells the injection ecu to limit the excursions of the EHA current changes so the idle RPM doesn't "hunt" too much.

When the WOT switch is closed (which occurs whenever the throttle plate something like 60% to 100% open), it puts a voltage on a different injection ECU pin which "tells" the injection ecus to ignore the O2 sensor signals completely and add extra current to the EHA valves to lower the A/F ratio from ~14.7:1 to ~12.5:1 to make maximum power.

Yes, it's just two on-off switches inside a common housing -- not a variable resistor.