erratic idle + loss of power

Help! I have had an intermittent fault with my V70 which has gotten much worse lately. It started off with an intermittent hiccup at high speeds. This then developed into an erratic idle, sometimes reving up and staying at 1500 rpm in park. Final straw came when going up a steep hill the lack of power left me half way up. Volvo dealer "cleared all fault codes" saying it was the gearbox kick down motor. I got it back and it all happened again. Took it down to my local garage and there were no faults logged in the ODB II systems, even though driving down there the car wouldn't exceed 25mph flat out. It runs the same on both gas and petrol(lpg conversion). I have cleaned the throttle body, replaced coil, plugs and leads. Any thoughts ?

had/have a similar problem. in my case i now think its down to bad petrol from a previous fil up as it seems to only happen when the tank is nearing the 10L mark and a brisk drive revving the nads off the car will clear it. could be bad petrol, MAP sensor, TPS, distributor cap and/or rotor arm, ICV, coolant temp sensor, vacuum leak (would need to be a big-ish one to affect a MAP based EFI system tho) or a combination of any of the above. as yours is an auto there may also be a sensor or microswitch playing up on the box so also consider that tho i wouldnt think a sensor or switch on the box would cause idle problems and hesitation/power loss.

Fuel Pump relay?.... Cheers Jod