Pontiac Repair: 99 Chevrolet Malibu 3.1 L, losing coolant, hesitation problem

Question
Hi, I have a 99 malibu 3.1 liter engine. Last week I took it in to the shop due to intermittent hesitation both while driving and idling. Also, it was losing coolant and getting hot. The guy that I took it to did a diagnostics test on the car and called to tell me that the intake gasket needed replacing because there was coolant in my oil and the gasket was busted. He said that would be $600 and he also informed me that it had an air pump which is malfunctioning. He said that the air pump needs a combination valve. I have never heard of that and was wondering if he's really telling me the truth. I did have him fix the intake gasket for $600 but did not have the comination valve repaired as of yet. However, the car is still hesitating and my low coolant light came back on last night but didn't stay on. I plan to take it back to him because something isn't right with that. Any ideas why it would still leak coolant and why it hesitates? Also, is there such a thing as a combination valve? it also has trouble turning over sometimes on startup. He didn't mention anything about that problem, but then again it doesn't do it all the time and I assume that nothing showed up on the scan for that. Any ideas so that I know what to ask/tell him would be greatly appreciated.

Thanks

Jennifer

Answer
Hi Jennifer:

First off the lower intake gasket is a VERY common problem. As for the lamp comming back on. That happnes. that engine gets air trapped in the system and when the air is expelled out the coolant can be low again and it may just need to be topped off. As for the air pump and valve yes those go bad as well BUT they will not cause a hesitation problem that I'm aware of. It can be a lot of different things causing the hesitation. If the car doesn't have any codes stored in it it's hard to find the problem. A few things to look at at a plugged fuel filter/fuel pressure issue. A MAP sesnor, TP sesnor or a MAF sensor. If it runs bad at idle I would also take a look at the throttle body and throttle plate for carbon build up. Hope that helps you out some...
Good luck :)