I have a 2007 Buick Lacrosse with a 3.8 liter and it has a cold start problem. I have checked fuel pressure, Maf sensor, map sensor, checked for spark, checked both cam and crank pids while trying to start vehicle. I was wondering if anyone has come across this problem and what could possibly be causing this problem?

Try turning the key to run but not start. Wait a second or two. Then start it. See if that helps.

how many miles? have you changed the plugs?

I have turn ignition on and waited fifteen seconds and still cranks and doesnt fire, also plugs are like new, I do have spark on all cylinders.

when it does start its a little rough and then smooths out, aand then I have wait for at least an hour before I can tried get it to do it again.

Only wait a second or two. The fuel pump primes and then stops. Wait to long and the pressure can drop off. Another test is unplug the MAF. It will run bad for a moment or two and then should smooth out. You can drive without the MAF plugged in, just drive easy.

Check the coolant temp sensor also. It may think it'* 95 outside.

Moved to Buick mechanical and maintenance section.

Well I checked the coolant temp sensor and it is good, also unplugged the MAF and it still wont start right up when cold, also checked cam and crank sensor, they are good, I did clean throttle plate andchecked MAF physically, it look new, also went ahead and changed spark plugs, but still have same problem, also checked O2 sensors pids and they are working properly, So I am not sure what else to look for at this time.

Bigdawg, there are two temp sensors. One for the light/gauge, and another for the pcm.