First my car is like day and night with the weather if its say below 60* it runs awsome, if its like above that 70 or 80 it feels like I lost 50hp. Now I know cars make more power in cooler more dense air but this seems extreme. What do you think?

Second in cold weather about 30* +/- when I first start it the SES light flashes and it runs like $hit until its warm (can actually feel it misfiring). Is this possibly related to tuning. My mods aren't that extreme see sig. Thanks


I'm going to post this in the Computer diagnostics as well.

 

Could be a sticking EGR trying to heat up the intake like it's supposed to. Don't run your car hard when it isnt at operating temp (including oil) therwise you can spin a bearing.

 

Guess I should add this to my sig. No AIR or EGR sorry

And its not the TB bypass either. It did it before.

I always let it warm up before I drive it. Everyone thinks I'm weird but I'm not one of those start and put it in drive kinda people

 

I would take a look at the IAT sensor or the MAP sensor. You may be the first person in history to have a bad MAP Those things are bullet proof you know. Check for physical damage and with a scanner for the values these 2 sensors are putting out. These 2 values should be changing with temperature changes obviously. While you're there, check the intake boot for tears or other leaks.

One other thing that I noticed on my car that varies greatly with temperature is the fuel pressure. Although it does not effect my vehicle, it may have an effect on yours.