Toyota Repair: Transmission, 2 quarts, toyota pickup

Question
I have a 1983 Toyota pickup. Manual Transmission, 22R 4cyl. About 167,000 miles. Runs great. I recently checked the transmission oil level and it was very low. I couldn't touch it with my finger. I added 2 quarts of 80w90 gear oil before I could touch it with my finger through the hole. After adding the oil I noticed great power loss. Any ideas on why this happened?

Answer
It shouldnt make a huge difference. If anything you would think it would spin better with oil in it.

One thought, you flushed out some gunk that was laying in the bottom of the trans and now its mixed thru the trans.
Run it hot, drain thoroughly and refill again.

Mike