87 tbi voltage spike

[Falkasorus]

Have an 87 tbi and long and short been some weird electrical issues but lately my voltage will go from 13v to 16v stay pegged there and then fall back. When it falls back the truck seems to miss almost die and come back. Ideas. Bad alternator. Or maybe the rough idle isn't related just seems to be. Could my map or iac cause the miss ? Thanks

 

[Yapay]

What are you doing when that happens? Driving, idle, city driving or highway? More details will help. Have you checked your alternator output? How old is your battery?

 

[Falkasorus]

It will do it at idle and while driving. Really notice it at idle. Put a new battery in it. The alternator plug looks new.