99 Jeep Wrangler 2.5L idle air control

I'm trying to replace the Idle air control on a 99 Jeep wrangler 2,5L. Not
sure if this is the problem or is it supposed to do this. So the new idle air
control I bought the plunger is shorter than the old idle air control plunger.
When I plug in the new IAC the RPM's jumps high like 3500 to 4000. So I
shut the engine off right away and took it out. I've gone all the part store
around (auto zone, advanced Auto, napa, etc) they all have the part which
they say is for the 99 Jeep wrangler but the plunger on them is shorter. So
now My question is the new one with the short plunger, when I replace that,
does it normally do what it did the first time which is high rpm and it'll adjust
itself to the correct height?

Thanks
Paul S.