High RMP al low speed after driving for >1 hr

[rubs]

Hi,

Normally the car drives fine at about 1500 rpm at <40 mph and about 2500 rpm at 70mph but for last few days whenever i drives more than an hour and then drives at low speed <35mph as soon as i press accelerator rmp jumps to 3000 and stays there and engine make shuddering noise. I Checked under the hood but found nothing obvious.
What can be the possible issue?
Car : 2001 i30 with 55k miles

Thanks
--rubs

[Nahkapohjola]

Originally Posted by rubs

...as soon as i press accelerator rmp jumps to 3000 and stays there and engine make shuddering noise....

Automatic tranny slipping?
- Have u checked A/T oil level
- Tranny gear changes to 1/2 or 3? Shudders always on the same gear?
- Manually pull to 1 and/or 2 ...same symptoms?
- check charge voltage level, clean tranny connectors, see http://www.cardomain.com/ride/748507/14 & 15
- run A/T self diag
- A/T uses TPS in 'kickdown' =gaspedal input. Check its resistance with multimeter. (Similar to Page 6.)
- download manual, free login http://www.phatg20.net/ ...theres detailed troubleshooting charts.

.