Hi! Guys

ive got a ford escort 1998 S Reg 1.6 Ghia

car drives fine very smooth etc..

but when i start the car up it rev's it self up to 3000 revs and the back down to 1000 and it looks like its about to cut out but it doesnt cut out

when i drive the car its fine doesnt rev it self

but when i change gears you get the feeling the engine is rev'ing it self..

also there is a rattle from under the engine ive not been able to look to see what is rattling but could this be a link to the engine rev'ing it self??
when i rev the car in park the engine is fine and there is no rattle

can someone please advice me on how to repair the rev'ing problem??

The revving will more than likely be the Idle Control Valve (ICV). Needs taking off and cleaning

Take off the throttle body and clean thoroughly in petrol or thinners, also clean out the idle speed control valve or get a new one. The problem could also be the throttle position sensor which bolts to the side of the throttle valve.
Not too sure about the rattle, could it be the clutch, or release bearing rattling in the gearbox, also check gearbox oil level.