my dad's 1990 2.9 automatic granada has got a problem that i'm hoping somebody on here can advise on. basically it has an erratic tickover but also when running along at low revs/waiting in traffic it surges/hesitates.

He's changed the TPS (to a second hand one so may still be this...?) and he's changed the idle control valve. he's cleaned out the air intake using carb cleaner too i think. Any other ideas what could be the problem?

thanks

 

air leak maybe

 

Check the vac can on the gearbox, if the diaphragm is split, it allows air in and can also make the changes at different times, these are about £15 new and a doddle to change, but if wanted can get adjustable one, so you can alter the change points to a degree.
tabetha