Hard start when cold, fine after that

I have a 1999 Malibu 3.1L. It has been starting hard first thing in the morning or when it has sat for an hour or so. You may have to crank it for 5-15 second and then it will start and run fine. Once you have started it and don't let it sit for to long it starts right up again.
We just had to replace the fuel filter as it crapped out, but this problem was happening before that.
Anyone have any ideas on what I should look at? Thanks

Hello. My 98 Malibu had a similar problem. When starting, I had to give it gas while cranking and then it fired right up and ran great. You might try that to see if it helps. Turned out the IAC (idle air-speed control) was bad. Could be a bad sensor somewhere as well - any check engine light?

I haven't had the IAC checked. It just put up the check engine light a couple of days ago. Pulled the codes at Autozone; 420 catalyst below efficiency. Which could mean about anything.
Could a bad O2 sensor cause the same problems?
How difficult/costly is the IAC to replacE?

:popcorn: I have a 1999 Malibu 3.1L. It has been starting hard first thing in the morning or when it has sat for an hour or so. You may have to crank it for 5-15 second and then it will start and run fine. Once you have started it and don't let it sit for to long it starts right up again.
We just had to replace the fuel filter as it crapped out, but this problem was happening before that.
Anyone have any ideas on what I should look at? Thanks

The IAC is not a difficult fix. I don't remember the cost, but it should be reasonable (under $100). I would start with your trouble codes. I don't have the manual in front of me, but I think DTC 420 is the catylitic converter. These are usually warranted for a while (but yours might be old enough to be beyond the warranty). Try a google search on your DTC and see what you can come up with. The downstream O2 sensor could give this code also - check the connections on your O2 sensors.