Steampunk as a genre goes back a ways- some claim Verne & Wells as its progenitors and Wild, Wild West as a mainstream manifestation- but it really didn’t hit its stride until the late 80s. And even then, it would be a while longer before it got into the consciousness of fans of mainstream sci-fi, horror & fantasy.Yeah in the early 1990s even most SF nerds didn't have a particularly clear idea of what "steampunk" might entail, if they were even familiar with the term (it didn't even begin to get popularized until The Difference Engine in 1990, though it does technically predate that I believe).
And as a result, most people's vision of steampunk in that era (and really until the very late 1990s, I'd say) was just extremely romanticized "Victoriana", with, a most, maybe a small helping HG Wells or similar thrown in (despite Space 1889, the original Wild Wild West etc.).
I feel like the 1999 Will Smith Wild Wild West was probably the end of steampunk being at all mysterious to people though.
I can definitely see the concept of steampunk Iron Man hitting players pretty damn hard in, say, 1992 or 1993.
As an amusing footnote, a couple years after I’d moved away from Austin, I stumbled upon a piece of sci-fi from a German author that was illustrated with an armored man with a flamethrower. Unfortunately, my German wasn’t good enough to find out if he had any other similarities to my villain (or Iron Man).