stalling problems

[tinman5789]

Need some help I have an 89 5.0 lx most of the usual mods I have installed the 3g upgrade I have underdrive pullies anyway car is fine till I switch on the ac or headlights after that it will stall or idle quality is very poor. alternator is putting out 14.7 at idle and around 13.5 with ac on the tps is set at.98 everything has been cleaned and adjusted I am pulling my hair out

 

[HISSIN50]

How much does the voltage drop with the AC or headlights on?

Consider the IAC not upping the idle to compensate for the additional load of the AC or alternator output.

 

[tinman5789]

output drops out around 12.8 to 13.5