If it still idles poorly in stock then the issue is in the truck and should be checked out. Otherwise, your edge is like a bandaid on a compound fracture.
No necessarily. It could mean he needs a custom tune. I've heard of quite a few 04+ with the gotts mod running lean and needing a tune to fix it
Yes necessarily. The custom tunes only fix programming issues. Commercial CAIs are a popular example because they have to be adjusted for. The reason being the sensor is out of calibration when you add one. The sensor thinks x amount of air is passing through the intake based on a function designed for the "X" inch diameter of the stock sized intake. With a larger performance intake the diameter increases by "Y" inches so you have x+y air passing through but the sensor only reads for "X" diameter and is not even aware of the increased diameter. The custom tune readjusts the sensor function to account for the extra amount of air passing through the added diameter "Y".
To be sure I did a small experiment a while back that involved the truck's MAF sensor readings and the gotts mod. I already had flowbench results from another member who had tested out the gotts mod's peak airflow so I knew scientifically that it did, in fact, provide increased air flow over the stock intake. The results in a nut shell are that with the gotts mod the truck recognizes the increased air flow and is able to adjust fuel accordingly. If the truck had not seen any increase in air flow or even worse, a decrease in airflow which could be seen from the engine still using the same amount of air but the sensor reading less flow due to the larger intake diameter.
http://forum.gopowerhungry.com/conversation-pit/3301-finding-sweet-spot-mileage.html#post36692
The gotts mod is different than a commercial CAI. Yes it brings the internal diameter up
at the point of peak restriction to nearly the same as commercial CAI specs but it does not increase the internal diameter of the sensor housing. If the sensor housing does not change then the sensor only reads diameter "X", thus not needing any adjustment in the calculation. Also, some of the 04s and 05s ran lean from the factory with the stock intake. The gotts mod is often used as a scapegoat because it increases air flow but does not have massive studies done on it because it is a $15 mod and nobody wants to spend a $100 on a dyno to prove 5-10 horsepower at top RPM.
If there is a mechanical problem it will only make things worse. It will force the truck to idle higher when there are mechanical causes that would otherwise make it idle slower. Tunes are written for trucks that are in optimum condition.
If you had a broken leg and couldn't run because it hurt, I could pump you so full of drugs that you wouldn't feel it. Then you could go back to running. Is it good to run with a broken leg? No, the broken bones would only get worse and even cause other tissue damage.
That is why it is critical to have the truck mechanically sound before you add any performance tuning to "correct" computer controlled components.