Is the check engine light "ON" when the engine is running .
How many miles on this engine .
Did you check for malfunction codes . if not check and let me know.
If the check engine light is not "ON" then have your Mechanic clean out the Throttle body as a build up of carbon in the throttle plate will cause you this issue that you are having .
Also if all is good and no Engine malfunction codes, then check for transmission codes, as a bad Torque converter will also cause this issue ..
Need any follow up help then please get back to me with the reply button, and not the poor or bad service.
This way i can get back to you or suggest another expert if needed.
If i do not get back to you then i may be off line, and when i get back online i will get back to you..
Your deposit does not pay me until the answer is rated in a positive way,
Not rating or a bad rating does not constitute a refund.
If you are not happy or you have sorted out your problem before the answer then please let me know with the reply button .
Kind regards Greg.