You've just found out why "Stop Leak" is good for radiators but bad for heater cores and useless for HG repair. You may have to replace the heater core as well. A cooling system pressure test will tell you that the system is not holding pressure. If you can find no visible leaks then probably HG.If the coolant is leaking into exhaust then thick white smoke with a sweet smell will be unmistakable. If the coolant is leaking into cylinders there will be anti-freeze in theoil and you will also see thick white smoke from the exhaust. A $20 oil analysis will show anti-freeze in the oil if you can see no other signs like milky white color. Right now it looks like a HG to me.
So here aremy considerations:
1. How much longer do you intend to keep this car? It has 204K and is a 93 after all.What's its book value? What can you replace it with.
2. What if they find more things to fix when the heads areoff ?(believe me they always do) Ifa warpedhead needs too much shaving it may require replacement. Will the $1000 also include a valve job, which I would recommend anyway since the head is off. Will you be able to or want to spend the extra?
3. What shape is the car/engine in? Compression good? Rust? Wear'n tear?
4. I would also recommend sending the injectors to "Witchhunter" for testing, cleaning, etc. This is quite cheap but since most of the labor has already been done is not a lot extra.
5. Life has a way to reward thosewho have just spent a $1000 on their car - by bringing about an event that destroys the car or coming up witha reason to spend another $1000.
6. Never get emotional about cars -you will make wrong decisions.
Here is a product that I have heard works and will not block the heater core. The trick is you must flush ALL anti-freeze from the system first. I would also replace the heater core and back flush the rad.
If you just want to keep this car going for another year or so this may be a good way to do it without spending the $1000 and you will probably not loose much to try.