I have a 87 turbo II and under boost [9 lbs] it has
been slipping in 2nd and 3rd gear. My question is,
I want to verify that it is the clutch, is there a way
I can verify?

 

It's likely the clutch. Replace the clutch, pressure plate, resurface the flywheel, replace the pilot and throwout bearings. Whenever I pull the tranny, I also replace the front and rear transmission seals. And if you have the flywheel off, might as well replace the eccentric seal as well.

 

Well, as usual Aaron sums it up qite well.
I would be easy on the equipment, as if it keeps slipping and with the heat build up, the flywheel condition may be impacted.
On mine, when it was pulled, the disc was still in good condition, but the pressure plate didn't have the clampping force it once had, therefore allowing the slippage.

 

Thanks for the help guys.

 

I had a somewhat similar problem. The clutch would slip under hard acceleration in the higher gears only (4th and 5th.) Turned out to be the clutch slave cylinder. Replaced it with a new one, and it's been perfect for 3 years now. Somehow, the old one was hanging up a little and not allowing the clutch to return fully when I let off the pedal. Don't know why it only did it in the higher gears, though. When I disassembled it, I found nothing unusual inside. Might be worth a check before you change the clutch.

 

Good point. Just make certain the clutch pedal has play at the top. If it does, throwout bearing has released from the pp.