Is this the clutch slipping?

[Rickety Rhino]

My Tercel is having a problem I think might be the clutch, but I'm not sure.
When I'm going up a hill in 4th or 5th gear with the accelerator pedal
all the way down, the engine starts to race and I lose power. This happens
before I would normally downshift (it's not lugging yet).
If I downshift earlier, or don't have full gas on, it doesn't happen. I don't have
any problem in low gears, even on steep hills or when starting.

Is this the clutch slipping or something worn in the tranny?

I did the clutch pedal checks in the Toyota repair manual, all OK:
- The clutch pedal height is within specs, so is the pedal free play.
- The release sector has 7 notches remaining (6 minimum per manual)
- I did a test from the Chilton's manual where you're stopped, with the brakes on,
and while in 4th or 5th gear, slowly let up the clutch pedal and see if the engine
stalls or the clutch slips. My engine stalls after some bucking.
The clutch has never been replaced to my knowledge (if so, it was more than
160k miles or 14 years ago). So it has a lot of miles on it, but I don't want to
replace the clutch unless I'm sure that's the problem.
'84 Tercel 4WD, manual tranny
Thanks for any advice,
-Rickety Rhino

[Gasoline Fumes]

Yeah, that's your clutch. If you're doing it yourself, pull the engine not the transmission. Much easier in my opinion.

[takza]

Just to be sure...I'd adjust that sector down to 4 notches or so...been running mine that way for 3 years or so. And check the cable for binding???

My sister had one of these with oil on the clutch (rear main)...slipped like crazy...she drove it at least 2 years that way.