I tested some slowdown utility and so far the one that grabbed my attention is SLOWDOWN.EXE 3.10 by Bret Jonhson. I'm a bit puzzled though that it dont seem to have preset for 386 option, it skip directly from 286 to 486. Maybe under the hood the /286mhz:## and /486mhz:## are just preset to the same timing routine so to keep it's command line help concise he skipped that one, maybe he did not had the time/equipment to build the /386mhz:## equivalence table ? I browsed the documentation but found nothing in that regard. If someone is trying to target an 386 I guess he will have to find the corresponding 286 or 486 equivalence.