[Blue Bowtie]

That lump of material was added to the plate to prevent stumbling on throttle tip-in. The transition of air flow from the IAC passage at idle to the throttle plate is not as smooth without that lump in place, and the resultant erratic air flow can be too much for the PCM to calculate fast enough to adjust injector PW.

Before modifying the TB, do some research. One of the common modifications is to install a 56m TB from a 1998+ Quad4 form a salvage yard donor and eliminating the small bore entirely. Many people who have done this also eliminate the clutch fan and install an electric fan to reduce parasitic drag and increase available power.

If you change to a cold air intake, be sure to install one which actually draws air from the front of the radiator support, and not from the engine compartment. Do some measurements there as well. You may discover that the factory air box and oval inlet through the radiator support is larger than the rest of the inlet ducts. Again, find the restriction and address that first.