Accelerating problems!

Right now I have my engine torn apart because I'm changing my head gasket(among other things). The problem is that when I let off of the clutch, the RPM's drop way down. The engine almost stalls out. It seems that the acceleration suddenly dropped, and has been getting worse. The car makes pulling out into traffic dangerous. I also noticed that there was a large puff of smoke behind my car while I was accelerating. All of my coolant keeps boiling away because my car keeps overheating. My engine overheats because my oil levels keep dropping. There may be another reason for my oil loss besides the leaking oil pangasket(replacing it).
I also noticed my exhaust manifold gasket is leaking. Besides that, my exhaust manifold is cracked in several places(explains whistling). My harmonic balancer is also off-balanced. I'm replacing that at the same time. I'm thinking that I may have blown a head gasket. That's the main reason why I'm changing the head gasket. It seems the further I dig into this car the more problems find. I'm wondering if the catallic converter is clogged, causing too much backpressure. Any other ideas of what could be causing this problem. BTW- The car is a 1990 Celica ST with a 1.6L DOHC 190,000 miles.

Also the engine idles with only a small amount of variation. Once I get up to about 40, it seems to run better. It seems to have no compression to me. I haven't noticed but a few drops of water in the oil. I haven't drained the oil yet, but I will today. I'll give an update tonight. Also, this is the first time I have ever dug this far into a FWD vehicle. This is a new experience for me.