Ford Repair: 95 ford probe overheating, coolant system, air control valve

Question
I've had a radiator replaced, new hoses, new distributor, new heat sensor & one fuel injector replaced. the car has only 50,000 miles. Everything ran fine for about 5 months and now the car is stalling in traffic and appears to be overheating again. There appears to be rust colored dust under the hood. A mechanic suggested that there may be a leak in the head gasket or core and said it isn't worth fixing because he would have to take apart the engine to determine the cause. He also offered $100.00 for it since I hinted I may junk it which made me suspicious. I've heard of a sealant called Blue Devil which worked wonders on a friend's car. The car is in Maryland as my son was using it at college and I would like to drive it back safely to New York before disposing or fixing it. Any ideas as to what may be the problem, what should be tested and if this sealant will work for the trip. Thanks for any help or suggestions.

Answer
That is very low mileage for a car that old. Those are nice cars too. I would have taken insult to the $100. I definitely wouldn't be going back there. Here is the first thing you want to do. The color description tells me that the coolant system either is now, or at one time very dirty. Flush the coolant system with a cleaner. Then flush the coolant system and add a cleaner. The thermostat can be a pain to get to on that year probe. So be patient, but replace the thermostat. You need to have a clean coolant system so you can find out if it has oil in it or not. The stalling maybe due to a dirty idle air control valve and throttle body. I have many posts if you will take the time to go look, with very detailed instructions on cleaning them. The overheating in combination with the drivability issues can be caused by clogged catalytic converters, so have them checked. Most Muffler shops will inspect for free. Can you give a time line for the replacement of all the parts listed along with the symptoms at the time? If the parts were all installed by the mechanic that offered you the $100 it tells me one thing about him. He is what we call a parts hanger, and has very little ability diagnosing problems. The overheating is a problem, meaning you should not drive the vehicle until solved. If the head gasket is defective, the car should be well worth the money of replacing.