Overheating

When driving on the highway, the temperature is normal but when I exit and slow down, the car overheats. I pulled over and noticed antifreeze gushing from under the hood so I popped the trunk. It was coming from the reserve tank. I did notice earlier that the reserve was too full.(I just bought this car, first highway trip) Now, the excess coolant is out, it is at the right levels. The car cooled and I got back on the highway to continue, got caught in traffic and had to slow down, the car overheated again. I pulled off and heard a strange sound, once again popped the hood and found the antifreeze in the reserve tank boiling. It wasn't leaking anywhere, just boiling in the tank like a pressure cooker. Where should I start here to find the problem? My auto knowledge is pitiful but I can't afford a mechanic. Anything I can check or replace myself that doesn't require more than a Chilton manual and basic tools?
EDIT: just ran the car until it overheated. When I initially started it, the radiator fans were on. After about 5 minutes, they shut off and didn't turn back on again. I waited about 10 minutes, they never came back on and the car overheated. I turned it off, restarted it to see if the fans would turn back on, they didn't. Why would they work upon initial startup and quit when the car got hot? What should I check here?

I also have a chevy lumina with the same problem except my fans always work. But your car overheats and the coolant leaks could be due to an intake leak which is a very common problem for the chevy model. It can be a little pricey to fix but I usually keep water in my car until I can save up the money to get it fixed. I don't have to put water in it often maybe every two weeks or so. I hope this helps

Engine Cooling problem
1996 Chevy Lumina Automatic 150K miles

It has a new thermostat and water pump. I check
the water and antifreeze before leaving the driveway.
Any ideas?

Thank you. I will get my son-in-law to check the fans.
I need to know more about cars now that my husband
has died and I know so little.

I'm saving answers for my son-in-law. After flushing the
radiator a few times it seems not to be overheating now. It could start again. Thanks

Today I had driven around several places and it quit
suddenly today. As is usual it would not start again.
I left the car and went into an air conditioned business.
Less then an hr. Later I went out and it started right up.
The heat gauge did NOT go up this time but it seems
like something is shutting down when the car gets a
little hot. I sure couldn't take a trip in it if its over a
half an hour or so. Its too hot to get out and walk far,
WHAT A PAIN!

Where are the cooling fans and relays? We are at a loss.
And the car is overheating again big time. It doesn't help that somehow I didn't put the radiator cap on
tight and its lost on the road. I will buy a radiator cap
but what next? Thank you

My A/C clutch/pulley was making a high whining noise so I figured it was about to go out so instead of spending 100+ dollars to put on a new compressor, I measured the serpentine belt to where I could bypass it, I did. And now (after double checking the belt route, ) My car overheats real bad. Could I have reversed the water pump by any chance?

This is the car. It is still overheating or has started
again. I thought it was too old to get codes but I'll
take it in when I can get it to stay cool long enough.
The engine light has been coming on. Thanks.

The fans etc. Seem to be o.K. According to my son-in-law, He tried the new radiator cap and we
thought we had it because it went a few days
without overheating or stopping on me. I even
drove it on a 30 mile trip. Both ways with no problem. Going home I was more concerned because it was dark and my 10 yr. Old great-grandson was along. I didn't want to get stuck and have to walk in the dark. Then yesterday was a nightmare. We went to church with no problems and afterwards went to my son's and daughter-in-law's house. We were there about an hour and started home (about 2 to 3 miles away). When we got within under a mile from home the car shut down. It began cutting out and missing and then stopped. It would not start
again so we walked home. After it cooled down it
started and came home. After a rest we left again.
I was going to take a grandson and the great-grandson to my son-in-law's house. We didn't get a
1/2 mile when it shut down. The two of them and
a man going by pushed it into a gas station. After
a rest and adding a little gas it started up and shut
down less then 1/2 mi. Later. After 3 more stops I
suggested calling the son-in-law. He pulled the car
into a parking lot, took me home and the other two
to his house. I just called over there and the grandson said his dad was going to try to start it. I told him to suggest getting codes read when he talked to him again. We don't have cell phones. During these stops the heat gauge didn't say it was hot but my son-in-law still thinks something is shutting it down when it is just a little hot. As I said before it has a new thermostat and water pump and now a new radiator cap. Water is not leaking out and fans are working.

I purchased this car cheap. I plugged my code reader up and put a throttle position sensor on it and it did not fix it. I also put a idle air on yesterday with no fix. I have a temperature sensor and a fuel filter I am putting on today. The car runs very good on the highway as long as air is cooling the engine, but driving through the city it gets warm and stalls but cranks right back up. I do have to park it and let it cool off before it quits stalling. Any help or ideas would be appreciated.

Thank you so much. I am ready to talk to my son-in-law.
I pray this works. It sounds logical and shows effort and
thinking on your part.