I got this substance, the lab tests came back 'unidentified'. It has no odor but when it burns it smells like semen, so I technically have no idea what I have.
But assuming it's 4f-mph, the drug isn't that good. Like many other fail-stims, it sits in limbo somewhere between recreational and functional. Seems like the main effects wear off too fast to be used at work, but the dose can't be pushed into euphoric levels without going psychotic a couple hours later. Redosing more than once is a complete mistake.
After going into psychosis with it the first couple nights and dosing way too high, just treating it like MDPV, I've found that for me it's going to be in the stash for a while. I'll pile on 5mg of it onto other drugs when i need a little clarity or energy. I've mixed very small doses of 4f-mph with 3-meo-pcp and found a very pleasing synergy around <5mg 4f-mph and <10mg 3-meo-pcp. Wouldn't want to really push either much farther.
Haven't tried 3-fpm but it doesn't sound all too useful, perhaps a fun time. For now, best bet on stims is probably amp powder.