My 98 Malibu is kinda running like it has a bad catalytic converter. At first I couldn't go over 30, then 40, then was finally able to hit 55 but over that it wants to sputter and sounded like it wanted to die... also when reving up to 4k rpm it sounds like a gremlin was trying to bust out of the air filter. Also looks like the ac is dripping (Not sure what part of the ac this is, but its back towards the firewall but the ac lines go to it.), but I always have a small river of water under my car when after I stop and let the car sit for a few hours, far to much water for just an ac condensation. Its more like 1/2 to full bottle of water.

I needed to get the car home to try and work on it to make it run, So I drove it 22 Miles home. When I got home I opened the overflow to find it not pressurized, like normal. Its 50ºF right now out side and it wasn't steaming like it was hot, didn't smell hot, so I figured it was safe enough, dipped my finger almost to the surface and felt no heat, plunged my finger into the coolant to find it colder then room temperature water. Not sure if its important either but heater works fine, gets nice and hot. And the car did not over heat at all.

Also now that I can drive 55, it idles rough. Also I have check engine lights, P0171 (Running Lean) and P0300 (Random Misfire) its been running fine with the P0171, and the P0300 didn't start happening until this problem happening. I think this injector technically still needs to be replaced. Also have a squeeky idler pulley sometimes.

Just so everyone knows, about 1000 miles ago, I did a head gasket job on this car. I had water in the oil, oil in the water so I figured might as well check the head gasket while I am down there anyway. So all new gaskets from the head up, new injector to fix a P302 code, I did have P0303 but it got better after 3 tanks with injector cleaner. Also has a new mass air flow sensor, that went out a couple weeks ago.

Any ideas?

if you drove it 22 miles and it didnt overheat and the heat works there is nothing wrong with the cooling system. most lean codes are vacuum leaks or lack of fuel pressure, thats what i would check since its easy.

But I am fine running lean... been that way for a month. The imediate issue is the running issue... any time I floor it, it sounds like a grimLin trying to bust out of the air filter.... very slow and poor acceleration. My dad told me it sounds like a timing issue. But i don't know myselk

You don't get timing issues with newer cars. But when your fuel pump goes it starts to lose pressure. Fuel filter or leak can cause issues too, the computer counts on having a certain pressure, and less means it runs lean. Any air leak the pump sees as being lean too. The car tells you what is wrong with it you just have to listen

I actually took it to a professional for diagnosis and they told me that my ignition module was bad. Replaced that and it'* all good now... still running lean but I found and so did the shop. Hairline fractures in the front of the upper intake

thats an air leak. not real common on that engine though to have problems like that.