Performance chips? 93 4.9l f150

i was wondering about this performance chip ?http://cgi.ebay.com/ebaymotors/REAL-PERFORMANCE-CHIP-GAS-SAVER-FORD-F150-1994-4-9L_W0QQcmdZViewItemQQ_trkparmsZ72Q3a727Q7c66Q3a2Q7 c65Q3a12Q7c39Q3a1Q7c240Q3a1318QQ_trksidZp3286Q2ec0 Q2em14QQhashZitem190266751701QQitemZ190266751701QQ ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories. i got a 1993 f150 4.9l f150 4x4

It sends a false signal to the PCM (Power Control Module) through the IAT (Intake Air Temperature) sensor. Maybe someone else could clear this up, but I think it is simply a resistor inside a box that you could by at Radio Shack for 50 cents. It sends a signal to the PCM that the air charge is colder. This changes the mixture and changes the advance on the timing. They put it into a box to keep you from seeing what you are really getting. Does it work? I don't know.