LScowboyLS

this is sounding more and more like ECU caps - O/D light on is another sign, and that ammonia smell is a dead giveaway

you know 93-97 are the most common years to have ECU caps fail, this is a known design defect, please read this post by ECU engineer Yamae

and remember - ECU caps do not have to be obviously leaking in order to be failing!