v8 prob

just got the wife a nice 3.9 v8 auto and having a teathing problem and need some help / advice please ... it runs great and starts on the buttom however when selecting drive the revs drop and sometimes cut out same if you are driving along and come to a stop it still ticks over great but change into reverse and the revs drop and sometimes die but they sometimes drop to just about dying but come back up to normal tickover ... any ideas guys please .. it has 113,000 miles with a full service history right up to 100,000 miles from 3 years old

Ignition amplifier module. Just had to replace mine similar symptoms.

Is it expensive ? ... Where is it situated ? God I hate petrols I like my diesels all day long so easy to repair lol

Behind passenger headlight mounted with ignition coil. Just got both for 29.50 have it amp tested to make sure it is at fault.

Just to keep you all posted it was the stepper motor all good now

Well the it is an Idle Control Valve