SVT TB is a 60mm TB, some places mis advertise ot as a 65mm...
Most likely you are getting issues from the MAF and injectors. They are probably having calibration issues. This is the reason, sticking to the stock MAF and stock 17;bers is the best way to go.
However, your CEL could be from many other things. It could be anyt other sensor in the car. You need an OBD2 scanner tool or as advised before, go to a local autozone, or place that'll read the code for little to no charge.
I got these error codes: EEC-V error codes, P1100, P0172 & P0175, P1100 Mass Air Flow Sensor Intermittent, P0172 System Too Rich - Bank No. 1 & P0175 System Too Rich - Bank No. 2.
My solution was A MAF optimizer. The problem for me was a too rich mixture for idle. I'm still playing with the manual settings on the MAF optimizer.
My Cougar was stalling/quitting when the engine went from high revs to an idle, like at a stop, with the new MAF, TB, SVT upper and lower Manifols and the 19 LBs injectors. The mixture was too rich for idle.
When you increase the mixture too rich for driving, you have to decrease the mixture (rich) for idle.
The 75mm MAF just was not calibrated correctly for my setup.
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