Chrysler New yorker 88 high-low idle

I recently purchased an 88 New Yorker with a 3.0 As soon as it warms up a little and I drop it in gear the idle goes way up. Replaced the IAC valve. Still does the high idle when dropped into gear. No vacum leaks. What else could cause the high idle when dropped into gear ?

eh bud u might wanna look into checkin all your vacumes but most of all the fpm = ((fule pressure modulator)) we had the same problem but 360$ in parts just to fine we wasted our money it was the fpm all along flooding everything... The fpm is gonna run u 160$ but my dads car worked fine after that so check that out befor u go blowin all your cash keep me posted eh gl BUD

the parts we got befor we found the problem was ...fuel pump relay...plugs...wires...cap rotor ...tempeture sensor..