I recently changed my upper and lower intake gaskets on my 2000 Monte Carlo SS 3800 series 2. After i did that my car has gotten harder to start and it stalls out when i give it gas. It has a raw gas smell and it stated smoking. Can someone help.

 

Is it smoking out the exhaust??? Or around the engine? As far as the smell of gas, did you change the injector O-rings? Next thing is to check that the injectors are properly seated. Also look for vacuum leaks.

 

Its smoking out the exhaust. I kinda hate i changed the gaskets because the car was running fine but when it warmed up it would leak antifreeze and stall when you jump off the gas but it needed to be changed. Now it doesn't want to stay crunk and its smoking and it wasn't smoking. I don't won't to have to put in another motor then Ima be upset. I can crank it up and it will run but its running rough. Then the rpm drops so low it almost stalls out then the rpm will jump way to stop it from stalling out. But as soon as i place it in drive it stalls anyway.

 

OK, ok, we're getting somewhere. This is VERY important. If you did not change the UIM (that plastic plenum) and the smoke is white, I know your problem. First, stop driving it. Continued driving while it's injecting anti-freeze can cause the problem to become fatal, but right now, fix it, clean up the coolant and maybe an oil change, done, no harm. As long as she starts and runs, this is fixable.

There is a "stove pipe" from the LIM to the upper plenum. It is nested between two coolant feeds. The heat of that pipe will degrade the plenum and cause coolant to shoot in with your clean air. It may have been doing it for a long time OR had enough "gunk" keeping this problem simmered down. You have TWO ways to fix it.
1 - Replace the UIM. Get the APN unit, cost is about $100 after shipping.
2 - For a couple of bucks from the hardware store, tape and plug the two coolant ports on the LIM (they feed coolant up the LIM, into the UIM, through the throttle body and around). You don't have to do ANYTHING else. See the pic below (there are two stainless plugs on both sides of the stove pipe). For added insurance, fill the UIM with JB weld.

Personally, I suggest option #2. Since all the gaskets are new, you can pop everything apart and still re-use the gaskets safely. If you want to test that it's the stove pipe, with the UIM off, blow compressed air through one end of the UIM, holding your finger over the other, you will find it.

I've done this on my Monte (just to keep the coolant from warming the incoming air) and my father did it to his Grand Prix for the problem I believe you are having right now.

 

I'm having the exact same issue. This past weekend me and a friend did the upper and lower intake manifold gaskets and also replaced the two coolant elbows. While we were at it we also did plugs and wires. Car drove perfect Monday and Tuesday until this morning. When I went to start it the first couple times it would die right away. On the third try I gave it some gas as well and it barely started but then the check engine light came on and was blinking so I immediately turned it off. I did not smell any coolant but there was white smoke coming out of one of the tail pipes.