1999 Plymouth Voyager 3L head gasket

I have a 1999 Plymouth Voyager 3L engine with 110,000km on it.  I bought the van 2 years ago with 65,000km and had to have the trani rebuilt at 87,000km.  The A/C stopped working, the background lighting for all the dash instruments has stopped working so I can’t see the cluster at night, the check engine light is always on, they say that they checked out the code and there is nothing wrong.  And that was more than one mechanic from different shops.

So my new problem is the head.  The van started to overheat the other day so I took it in and they said that I had combustion coming into the rad?  So he said that it could be the head gasket or the engine needs major word.  

So my question is should I put more money into this thing or do I cut my loses?

Do engines run the same after the head is blown and the thing overheats and warps everything?

I just bought a condo and am very tight for money as well.  I also just finished paying it off in Feb.

Any opinions would help.  Thanks.