1998 Ford Contour high RPM and idle speed

I looked into the codes which are in the order you posted

p1506 idle air control over speed error
p0122 throttle positioning sensor low input
p0102 mass air flow sensor low input

sounds like it could be a vacuum leak look for disconnected or broken vacuum lines or have your mechanic check for leaks l

I tried to find the leak as you have mentioned but could not find any. Even mechanic told the same, but he said there were no leaks. Then he disconnected a jack, and he said that it would drive the car in default condition, the sound got better while driving after that, but when we stop the car, it shakes and engine seems to move as well. So what could be done. Btw thank you for the response. I really appreciate it.

Ok not sure if this is the cause of your problem but something you could look into

I found a recall listing for your vechile

99V194000:FUEL:THROTTLE LINKAGES AND CONTROL
NHTSA RECALL BULLETIN

Reference Number(s): 99V194000

VEHICLE DESCRIPTION
Model(s): 1998 Ford Contour
1998 Mercury Mystique
1999 Mercury Cougar
Campaign No: 99V194000 Mfg. Campaign No: 99S19
Number of Affected Vehicles: 153000
Beginning Date of Manufacture: 1997 JUL
Ending Date of Manufacture: 1998 APR
Passenger vehicles.

DESCRIPTION OF DEFECT
The accelerator cable may have been manufactured with a burr on or near the end of the cable sleeve interior.

CONSEQUENCE OF DEFECT
This burr could fray the core wire resulting in the accelerator not returning to idle when the accelerator is
released. This condition can result in the throttle sticking, binding, or causing high engine rpm.

CORRECTIVE ACTION
Dealers will install a revised accelerator cable that has a flared conduit sleeve end and molded on end fitting.

OWNER NOTIFICATION
Owner notification is expected to begin during August 1999. Owners who take their vehicles to an authorized
dealer on an agreed upon service date and do not receive the free remedy within a reasonable time should
contact Ford