94 camaro overheating

I have a 94 3.4 Camaro and its been having some overheating problems. I've been springing leaks left and right (freeze plugs, hoses and such) so I took it to a mechanic and since my coolant is orangish he said that it's all rusted out and corroded in the radiator, block ect.
Anyways, it sounds like there are just going to be more problems than what I want to deal with on this car so I am going to sell it, but there is one more problem. I was driving the other day and it started to overheat again. I made sure there was plenty of coolant, but still overheated.
I had replaced my thermostat a month ago and did again tonight but the same problem occurs.
Im thinking maybe its my heater core because I had my heater going when it started overheating the first time and the air started blowing cold. Now it feels like A/C when I turn on the heater even though the car is overheating.
What do you guys think?

probably got an air lock? Has the coolant level been going down ??
did you get a good thermy or just a cheap one
it could possibly be your problem

I was going to check the system for any air today but I dont think that that is the problem. In the past when I needed a new thermostat, the heater at least still worked (or at least i thought it did..) but the heater doesn't work at all now.
Yes I just got a cheap one, but it should still work if for at least 15 minutes.
And yes, the coolant level has been going down. I has previously been leaking out of the hoses, but now it's not leaking from hoses. It's been spilling out of the water resouvier. You know, backing up and spilling out like a toliet would do haha.
I'm thinking it may be a clog in the system or something like that.

I was going to check the system for any air today but I dont think that that is the problem. In the past when I needed a new thermostat, the heater at least still worked (or at least i thought it did..) but the heater doesn't work at all now.
Yes I just got a cheap one, but it should still work if for at least 15 minutes.
And yes, the coolant level has been going down. I has previously been leaking out of the hoses, but now it's not leaking from hoses. It's been spilling out of the water resouvier. You know, backing up and spilling out like a toliet would do haha.
I'm thinking it may be a clog in the system or something like that. you said you coolant was orangish could it have had dexcool my 94 ta uses it. it is orange in color and can not be mixed with ethalyn glycol antifreeze it could cause it to gel also did you open the bleed vavles that could cause it get an air lock when a system has an air lock it will not circulate properly so that could cause overheating and no heater it is most likely an air lock one way to break one is to repeadly race engine with ratiator cap off until thermo opens and the repeated serge of engine reving will cause the coolant to move up and down in radiator sometimes forcing out air try it could possibly help

when I did my coolant swap my car also started to run the temp up as I was trying to bleed the air out of it. I got the nose of the car up in the air higher to bleed air out . It worked for me

In my 99 blazer, I drained out the pink stuff, flushed the system and replaced with the green stuff. had to use the garden hose to unplug the heater core but it has been over a year and no problems. I hate the pink stuff..
As for the air lock, keep the cap off and let the fluid rise and lower in the radiator untill it is hot, have someone bring up your rpm's just a hundred or so and hold it there while you top off the fluid in the rad. and put on the cap and make sure the overflow jug is full to the hot level.
When your rpms are up while driving and the engine is hot it will suck fluid out of the overflow and replentish the radiator, slow it down and it will force fluid back into the overflow thus removing the air lock.
But if your system has had so many problems already, you may have a pluged radiator.
just a thought :smokin: