I don't kmow where information above came from, but Performance Red ES was not availble in 1998. Here is a breakdown of colors from Yellowmustangregistry.com
1998 Mustangs BY COLOR
Color Name Paint Code Units Sold
Black UA 32,326
Laser Red E9 28,174
Crystal White ZR 26,114
Dark Green Satin FU 17,060
Rio Red E8 16.971
Silver YN 14,560
Atlantic Blue K6 12,151
Pacific Green PS 9,929
Bright Atlantic Blue K7 7,074
Chrome Yellow BZ 6,283