Some help needed !

While driving on saturday the car lost power suddenly, pulled over and put it in drive and idel was very rough, almost to a stall. Reved it a ciuple of times and it was k, pulled away and got it home, though it seemed very under powered. Left it overnight and started it yesterday and it idled badly and almost stalling, doesnt seem to fire on all cylinders. Took it for a drive and it ran fine and idled ok when stopped. Turned it off and got back in later and it was all over the place again. Seems worst at idle and the problem seem erratic. Thought it might be poor weather on saturday as went through a lot of water but guessing thats not the case. Checked connections etc all seem fine, no loss of oil or fluids or coolant etc. Seems electrical to me.

Its a 97 300 sport with about 150k on the clock. Reading other posts seems like the TPS needs checking, if so, where is it and how do i check it. Any other suggestions ?

It sounds like it may be due to a fault with the coil packs on the spark plugs, does the misfire happen all the time or only when wet, the reason being it sounds like the problem is only when the engine is cold or damp

Don't think this model has coil packs. Does sound like ignition though, worth checking spark plugs, leads etc.

Thanks for the input. Will investigate further this evening. Is there anywhere i can get a 'map' of the engine bay, not at all familiar with whats under the bonnet of the GS ?

mine did this when i first bought it ,i thought it was fuel starvation as it was rough idling and had lack of power ,took it back to garage and they did some checks and came up with nothing so i put it down to a bad batch of petrol ,stuck some of that injector cleaner in it and filled it right up and all has been fine since .yours sounds like damp has got in some were ,buy some of that spray from the garage and give the leads and plugs a good spray.other than that could be a plug breaking down ,when were they last changed

ironically due a service and due a plug change ! Will try some injector cleaner and treat it to a full tank of fuel and see if that helps if i cant find anything more obvious tonight.

Right, had a good look last night. Reset the ECU and it seemed to sort it, car drives fine underload no problems. Left to idel and fine. Switch it off and back on agin and idle goes wrong again, thogh car drives ok. Doesn't seem to affect normal driving and its just the idel, though the problem is erratic. I have ruled out plugs, leads atc as it runs ok its just the idle. This leads me to think its the TPS. Any idea what to do ?

I would clean the throttle body first. Easier than messing with the TPS.

Thanks Colin, any guidance or info anywhere on the site for cleaning the throttle body ? couldnt find anything myslef.