GM-GMC: hanging rpm when shifting gears, shifting gears, throttle positioning sensor

Question
i have a 1994 s10 with a manual 5 speed and a 4.3 tbi that
has 160000 miles on it and is still like new...this truck
runs and looks like new with one execption.  when shifting
gears especially when cold the rpm hangs quite high and you
have to come to a complete stop to bring the rpm back down
to a normal idle....i've checked the resistance of the coolant sensor at the goose neck on the intake manifold and it follows the tempature in the inverse..around 50 its close to 4500 ohms and at normal temp its down to 450 ohms which is correct....also checked the throttle positioning sensor and its smooth from idle and full vacuum at 5 volts and full open throttle down to .5volts and little vacuum...also checked the iac valve and it is clean and checks fine...and the truck idle's perfect..the only thing i can think of is the map sensor that monitors both vacumm and speed...speed being the red flag since it takes coming to a stop to bring idle down....one other thing the dash temp never comes up to normal temp but the coolant sensor resistance says different and its been like this since new....i have not replaced any sensor since all voltage and resistances measure good...one other note  there is a filter on the map unit that i can't find out anything about but appears to filter vacuum..know this is wordy but its
its one i can't get a hold of..would appreciate an experts opinion...thanks very much...larry

Answer
Larry have you measure the pintle on the end of the IAC it should measure no more than 1 1/8 of an inch .If that checks out you may be on the right track with the MAP sensor my advice is to go by one of your local salvage yards to get one just about an GM vehicle will have one that will work it may just mount differently it usually have a spare in my tool box just for this reason as for the filter vacuum im not sure!!!????