ok most answers would seem obvious:
i have an intermitent fault on my 95 80 , some times i experience a "miss fire or power loss" at low revs when cruisin .. at worst i kinda feel the nose dip for a second , i have tried injector cleaner fuel addatives
and run it on shell v power fuel. that kinda helped but it comes back !! any ideas

 

id check for vac leaks