My '93 Eldo which has the same 4.9 engine won't run well on regular.
You could retard the timing a couple of degrees but you would likely
then lose in mileage what you gained at the pump. Some have reported
no real difference in performance. You could try some 89 and if you
get any pinging you can go back to 93.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.