cooling system - should i give up?

My radiator popped during the week, I noticed the temp gauge at high and the warning light came on. I pulled over and shut it down but the rad emptied it's contents on the motorway. I got a piggy back to my yard from a very nice man and couldn't find any problems with hoses so filled it up and turned the engine over, the water came flooding out again so I put a tub of irontite in, left it running for a bit, emptied it and left to set for 24 hours. I filled it up again this evening, turned it over and no leaks, also no water returning into the header tank? The water that was in there started to boil over and the rad popped again, emptying it's contents. The top hoses weren't hard, but very hot. The rad didn't dump all the water, there was still plenty in there until I removed the drain plug.
I've read that it could be the thermostat or water pump and most certainly a new radiator needed. Is there a sure fire test I can carry out to ascertain if I need a thermostat / water pump?
My heater matrix o rings have needed doing for a few weeks now too, I've got the bits, just not the time to change them. I'm not sure if this is relevant?
To be honest, I'm considering putting it on ebay, as it is, and getting something else.
1995 4.0 petrol, lpg (single point)

you can test the thermostat by placing it in a saucepan of hot water to see if it opens, whilst it's out run motor without stat to see if water is circulating, sounds like it's making a bit of steam, blocked hose or water jacket? flush the heater matrix out whilst changing o rings, if water ciculates without stat you will know it's the stat if not it's the pump or forementioned blockage.Good luck.LEE

you should have left iron tite in for 2 days as it says on bottle. also you need to take small pipe off between rad and hether tank this need to be carrying water round the system if blocked overheating build up of presure i would think that one of your prblems