Will a faulty MAP cause engine to idle roughly while in gear?

1. Worn clutch: If the clutch is worn, it may not be disengaging properly when you change gears, causing the engine to continue to rev as if you were still accelerating. This can also cause difficulty shifting gears or a slipping feeling when accelerating.
2. Dirty or faulty throttle body: The throttle body controls the amount of air entering the engine and adjusts the idle speed. If it's dirty or faulty, it may not be closing properly after you release the accelerator pedal, causing the engine to continue to rev.
3. Vacuum leak: A vacuum leak can cause the engine to rev excessively or idle roughly. The leak can be caused by a cracked or disconnected vacuum hose, or a malfunctioning intake manifold gasket.
4. Faulty idle air control valve: The idle air control valve regulates the engine's idle speed. If it's faulty, it may not be closing properly after you release the accelerator pedal, causing the engine to continue to rev.

Have you cleaned the throttle body bore and plate of carbon/deposits ? This can cause idle and off idle symptoms .

Sea foam from walmart or local parts store will fix this.

IAC could be the problem or the TPS is going. Also don't forget to thoroughly clean the throttle body..dirty ones cause 90% of bad running symptoms.

The first thing you need done is a scan of the TCM for fault codes

P0068 Symptoms - Engine Light ON (or Service Engine Soon Warning Light)
- Lack/Loss of power
- Engine rough idle Possible causes - Large vacuum leak
- Leaking air duct system
- Mass Air Flow (MAF) poor electrcial connection
- Manifold Absolute Pressure (MAP) poor electrcial connection
- Faulty Mass Air Flow (MAF) sensor
- Faulty Manifold Absolute Pressure (MAP) sensor
- TP sensor not seated properly.
- Faulty Throttle Position (TP) sensor.
- Dirty throttle body
When is the code detected? The Powertrain Control Module (PCM) monitors operation rationality check by comparing sensed throttle position to mass air flow readings
P0068 DODGE Description The Powertrain Control Module (PCM) monitors a vehicle operation rationality check by comparing Throttle Position (TP) to Mass Air Flow (MAF) readings. If, during a self-test, the comparison of the TP sensor and MAF sensor readings are not consistent with the calibrated load values, the test fails and a diagnostic trouble code is stored in continuous memory.

When is the code detected? The idle speed is less than the target idle speed by 100 rpm or more.
Possible Causes - Dirty throttle body
- Electric throttle control actuator misadjusted or damaged
- Faulty Electric throttle control actuator
- Intake air leak
- Poor electrical connection to the Intake Air Control (IAC) valve
Possible Solution If there are no intake leaks, clean throttle body, adjust engine idle and erase engine code. If the code comes back you may have to replaced the Electric Throttle Control Actuator (Motor) to repair the problem.

Do you have a check engine light on in your dash ?
It may be your throttle body is dirty. Run some SEA FOAM engine tune up in the gas when the tank is about 1/4 full, dump the whole can in, drive it for a while then let it sit. If rough idle continues you may have to pull throttle body and clean.

Your idle air control valve may be dirty or the wire harness may be damaged. First try cleaning the throttle body with throttle body cleaner and make sure you use all the can up and try to get the idle air control valve cleaned. A faulty or dirty idle air control valve will cause engine to stall when put in to gear from idle. Good luck and hope this helps. Keep me posted, be glad to help you get your car running 100% soon.

U can read the codes at home, here is the link to the way to do that.

http://check-engine-light-codes.blogspot.com/2006/03/gm-1983-95-vehicles-obd1-codes-self.html