Just bought a '97 T100 4x4 5VZ-FE MTX /w 137k. {smiles!} Trying figure out an intermittent but frequent high idle problem. I've noticed that the throttle body appears to close fully, idling at 1100-1600, however if I push on the throttle body rotating-lever-assembly, it rotates just a wee bit more -- and idle drops to 750.

The throttle and cruise cables have plenty of slack, and I've checked, according to the manual, the TPS resistances, the dashpot (what does that do?), and the throttle opener (what does that do?). All are in spec.
Engine off, the throttle assembly closes, but if I push it closed a bit more, it moves and spring back just a little. Maybe that's not a fair test, so I apply vacuum to the throttle opener, and now the assembly closes all the way and can't be rotated that wee bit more.

Does anyone know how the whole throttle body system works? I don't understand the role of the throttle opener and dashpot, and how the mechanical behavior of the lever is affected by vacuum, and other things. No explanation seems to be in the manual. Maybe I just need to pull the TB and adjust the stop screw?

Confused,
-Alex
'97 T100 XC 4x4 MTX
'95 SHO MTX