My 95, 3.8, with 88k has been using some antifreeze lately. When I recently opened the overflow tank and the radiator to check on the levels, there was a strange odor in them. It smelled kind of like exhaust gas and gasoline. The coolant is green, not milky, in the radiator. There is a brown scum coating on the upper part of the over flow tank. Sometimes there seems to be a sweet smell inside the car and under the hood. When using the heat, no smell is detected at all as would typically occur with a leaking heater core. The engine oil is fine, not milky either.
I'm not sure if the two are related, but I've been puzzled over a rough start problem that typically happens when you cold start the car for the first time of the day. It usually is fine for at least the rest of the day if not for the next day too. When first started, you think you have a serious tune up problem, but when you give it the gas or just start driving, it immediately clears up. I wonder if antifreeze is leaking into one of the cylinders causing it to initially run rough. I also checked the tailpipe, and it smelled and looked normal inside, though I should recheck it right when first starting it. At one point, there was noticed a large amount of white smoke coming from the tp not long after starting it, but I just thought it was typical of a first start up, but I didn't see it for myself.
Any suggestions as to determining if the exhaust really is getting into the cooling system? I imagine pulling plugs for green, maybe look at O2s for green, compression testing, which is a real PITA on this engine. I was hoping someone can suggest something cheap and easy (

I know I'm not asking for much) to diagnose this.
I checked for codes to see if there were any and if they could help with any of this. BTW, the CEL hasn't come on at all. These are OBD I or EEC-IV codes.
KOEO
116-Engine coolant temp higher or lower than expected
114-Air charge temp higher or lower than expected
(aka the sensors are out of range)
No continuous codes
KOER
536-BOO circuit not activated during KOER (aka circuit failure)
521-Power steering pressure switch circuit fault (possibly circuit failure)
Any suggestions on remedying these are welcome if you know what common causes of them to repair.
Thanks in advance!
This auto repair business is getting ahead of me with six needing my attention. That leaves me no more fall back vehicles!?!

