I have an 03 4.6 and it started acting like it was missing when taking off under light load and sometimes at cruising speed. Also at idle the rpms sometimes drop below 500 then return to normal and keeps fluctuating as I sit at a light or something. I have no check engine light and get no codes on my tuner. What confuses me is that I can put the pedal to the floor and it goes through the gears no problem. Any ideas?

 

Hmm to me it sounds like it could be IAC valve, how many km does it have?

 

112,000. Can the torque converter cause any of those symptoms?

 

It would be rare.

IAC valve as mentioned. Otherwise find someone with a scanner that can check live data (auto stores don't do this). You can get miss fire counts under mode 6. Doesn't need to have a code to do this.

 

Thanks for the help I'll check into it and see what happens

 

Replaced the IAC valve and cleaned the throttle body while I was there and the truck is running great. Thanks for all the help!

 

Sorry i didnt see this earlier, everything u mentioned happened to my truck, changed out the iac valve, truck ran perfectly from then on

 

This may seem like a dumb question, but how do I know if my truck is a 2v 3v or 4v?

 

Yours is a 2 valve.

 

Truck ran good for 1 day. Still missing or slipping when accelerating. Seems to happen more in the heat of the day. Gonna replace spark plugs and coil packs. Any other ideas would be appreciated.