few issues....

2010 aveo lt, auto with 77k

1)the car feels like it has a miss, a "surging" feel to it, yet theres no CEL....cars had the plug/wire recall issue resolved in the past like 25k miles ago, will the car show the code for a miss without the CEL?? what other possibilities could I be looking at??

2)car recently has the smell of antifreeze after parking and a walkby, not inside tho, upon checking under the hood you can notice a fluid/liquid on the black housing and beneath it right behind where the thermostat sits, it appears plastic, any chance this piece has developed a split/crack??

3)still have the ongoing issue with a rattle in the pass rear, dealership can find NOTHING loose, add to this that the car upon hitting the slightest bumps will "skip/hop" to the pass side in the rear, its as if the car is lifted on hitting a bump and set down a foot or more to the pass side, it simply kicks out to the pass side. My son recently drove the car and says he absolutely hates the way it handles going so far as to say it felt unsafe to drive. The tires are getting worn but still cant see anything as worn tires causing such a drastic handling problem, rear alignment drastically off?? was aligned previously at 54k....thoughts/opinions anyone??

There are a few possibilities to each area here:

1. the surging, with no CEL, i would first bet it is spark plugs. I don't know what the dealership put in yours, but they didn't touch my spark plugs. Almost everything else will throw a code aside from a torn/broken intake. The only other thing that will not throw a code is fuel/fuel pressure. But that is harder to check. Look over your intake for cracks in the plastic, most likely between the throttle body and the MAF sensor, which is like a foot of pipe. Then I would switch the spark plugs to new NGK coppers just because you said its been 25k miles. (that is th service interval for the spark plugs).

2, if you think it is leaking it possibly is. Whether the housing, or seal, etc. If it is cracked, and a small leak, replace it before it lets go and cost you lots of money.

3. This is the hardest on to diagnose online. Based on your description I would almost absolutely say rear control arm bushings. But I would hope a dealership would be able to see that. The car has a rear beam, so if this is your first small car with a beam axle, it might be a characteristic of the car. But it should more like something is actually broken. A bad strut or spring would cause this as well, but it is less likely to be missed be the dealer. I would check the bushings, and if they check out, then look at the bearings.

#1, my car does this too and sometimes throws a flashing cel but no codes, it goes away so i just ignore it.
#2, if it's cracked you should be able to see fluid leaking from it, replace it, or it could be a leaking gasket somewhere
#3, take it to a place that isn't the dealership, see what they say.