Irradic Idle and Surge

Towards the end of last season, my car started to have trouble finding it's idle. If I were to start it up, it would bounce between 400-900 rpms trying to steady itself out. It was worse in the cold but still happens when it's warm. I didn't make much of it as I was upgrading the size of the fuel injectors anyways this year. Long story short, I just got done installing new fuel injectors and there is still an idle problem. I cleaned the MAF, TB, air filter and IAC sensor. It improved a little bit but still has a problem. Now onto my second problem, after test driving the car a little bit, when I down shift and slam the throttle wide open it feels like there is a surge and it takes a bit to finally take off. Does anyone think that a re-tune will solve both of these issues or if it's a sensor issue as well?

Thanks.

If the injectors aren't oem then you have thrown the car way off and your asking for trouble doing any wot pulls. Check for codes, could be IAT sensor, fuel filter, quite possibly a vacuum leak(something I had and my idle would remain high for way to long)

Everything else is stock, but you installed bigger injectors??

No, i threw in a cam, bigger intake & tb, heads are ported, full exhaust, headers. I called my tuner and he told me the increase in injector size definitely needs a re-tune. But the eradict idle is a sensor. I'm think of starting with the IAC sensor although I cleaned the carbon off.

Before someone else asks...

You got the cam, intake, ported heads, exhaust and headers installed last year correct? And at that time you had it tuned and it ran fine? Then at the end of the season is when your problem started? Since then you've installed bigger injectors and still have the same problem?

Do you have any codes? I sense maybe a vacuum leak.

Yes, I did all the work and then had it tuned. The tune was good and the idle was good. Just towards the end of the year I noticed problems with the idle. A computer tune doesn't go bad over time, but a sensor might be. I had to go with larger injectors due to the engine leaning out above 5000rpms. Knowing that I was running injectors too small all year, I just thought that maybe the idle problem was due to the smaller injectors just being over worked or whatever. I changed out injectors and the idle problem is still there, so I really believe it's gotta be a sensor now. I cleaned all sensors and it got a little better finding its idle again, just not perfect yet. I'm kind of talking myself into the IAC sensor is going bad. I don't have any codes being thrown and I heard that the IAC sensor will not throw a code if that goes bad; but i don't really know how common that it does go bad. I'm hoping someone out there has had a similar problem and can pin point it something specific before I pony up 130 buck for a sensor. I also have not ruled out a vaccuum leak...but wouldn't that throw a code anyways?

well if you installed larger injectors after the tune, then you need to get it retuned. but I bet your idle problem is an IAC or vacuum leak