Help, car problems

Wondering if any one can help me with this. I have a 1994 Toyota tercel, the car has worked great (except the fact that it has always had a leak around the crank gear). Being a girl I didn't know you had to tell mechanics to flush your rad during a tune up. Any how, my rad was quite corroded (I didn't know) and then my car over heated due to no rad fluid. I had a new rad put in and the mechanic replaced the thermostat. My car was still idling hard and was a rough ride. I took it back and the mechanic then informed me it was the distributor, so I had that replaced (plus a full tune up). My car was still working horribly, so I went back to find out my head gasket was blown, they replaced that and sent my head to be replaned (it didn't crack). Then my car was leaking oil and I was putting in 3 liter's a day. I took it back, they redid the head gasket saying it wasn't sealed properly...he told me the sealant they used didn't seem to work properly on my head gasket. So, now I'm in the hole $3,000.00 and my car is still working horribly, stalling, hard starts, not idling well while in drive. I have to put my car in neutral every time I stop. I can't take it on the highway as when I stop to take a turn off it keeps stalling, I can't go through drive through restaurants either as I'm afraid it might stall. I went to see another mechanic, he told me my lower part of my engine is gone and I either need a new engine or get a new car!!! I was really hoping the problem was perhaps simple.
Has anyone got some good news for me, perhaps the mechanic is wrong??? has any one gone through this before? what should I do, get a new car, new engine or have this engine repaired.
I really appreciate any responses.

One thing I know for sure is that you need to go back that first mechanic and pummel him around the head and shoulders. Sounds like he just guesses as to what might be wrong and would eventually replace everything, one piece at a time.
I don't know what's wrong with your car, but in my opinion, you've already put too much money into it for these repairs. If you want to keep it, check the price difference between rebuilding the engine and getting another one. If you do decide to get it fixed, I'd go back to that original mechanic and see if he'd chip in for it since he didn't seem to know what he was doing to begin with. Again, just my opinion.