WHEN I START IT REVS UP LIKE I HAVE GAS ACCELERATED

the thermostat wont cause this... check the cold start injector. (in the throttle body).

it would usually be the tps (throttle positioning sensor) but you can also check the icv (idle control valve)

So many options...oxygen sensor, egr valve, pcv valve, premium gas.

If the idle speed is normal until you shift into a gear, the idle air control valve is probably raising the idle speed. Try unplugging the iac motor at idle then shift into drive.
If the IAC is raising the RPM the computer controls it, so for some reason the computer thinks the RPM needs to go up. I am assuming you do not have a check engine light on or you would have checked for trouble codes.
Just for the record, I am showing the same IAC for both transmissions on a 2.0 engine code 3.
Is it possible the battery was disconnected and the learn process needs to be done for the computer to know where normal idle speed is ?

I doubt it.
More often the high idle is a vac leak or problem with the idle air control valve.
Is the check engine light on ?

The idling may be a loose connection to the "idle air control valve". if the control valve connection is secure, then it could also be a bad Throttle Positioning Sensor (TPS). To test the TPS, tap it with a screwdriver while the engine is self-revving, and see if the reving changes when tapped. if its not the TPS, then try cleaning the throttle body.

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It is either your TPS (Throttle possition sensor) or your IAC valve (Idle Air Control). The TPS can be adjusted But the IAC has to be replaced. Both are not that expensive to do...

take a long look at the throttle position sensor and idle air control. Before starting push the accelerator pedal all the a way to the bottom of travel and release quickly. Now try to start. Sometimes the ECU loses track of where the TPS is and pressing the gas pedal on full and releasing can sometimes help reset things. One thing you must do is clean the interior of your throttle body by disconnecting the air ducting and getting in there with a cloth soaked in WD40. If you have an idle air control valve mounted on the throttle body remove it and clean the associated passageways and valve interior. Reassemble and you should notice a difference

If you have replaced the Throttle postion sensor (TPS) or have replaced the battery, sometimes the car will need an engine set up.
I had the same problem with my xj6 and I did an engine set-up and it has been fine for the last 2 years. Also with the idle doing what it did it had a very harsh shift when driving and changing gears.
The BAD news is the dealer has to perform the engine set-up using the WDS (worldwide diagnostic system) The set-up will set the kick down switch, it will calibrate and set the TPS and also perform an oxygen sensor orientation test.
With the set-up it will allow the TPS sensor to be adjusted to the correct factory specs.
Sorry you can't do this your self.
This is obviously if there is no vac leaks and the throttle butterfly is set to 2 thousands of an inch. (gap on the side when closed throttle) check with a feeler guage.
JPTCAT

tps sensor or an iac valve tps would throttle position and iac would be idle air control