Truck is bucking/bumping?

riding down the road today my truck started bumping, almost feels like axle wrap when taking off. But it will do it 4-5 times then stop for a minute or so. When I got out of my truck I smelled something burning, almost a sweet smell. Check fluids and did a quick look and everything seems fine. Had to go into work. The truck is an 02 limited 4wd 3.4

 

Sweet smell is usually coolant

 

It’s not a coolant smell I’m almost sure of it. plus I don’t know how coolant would cause this.

 

Don’t think it would cause it either. Just answering the sweet smell

 

I will second the coolant daignosis... from the passenger side of the truck look at the back of the throttle body. There are 2 - 10 mm hoses. When either one of these spring a leak the coolant collects on top of the motor and not until there is lots of it does it drip onto the ground all along giving a sweet smell.

 

You think the bumping is coming from the rear or the front?

 

Front middle. CEL came on, says it’s the bank one o2 sensor. Not sure why that would cause bucking but it’s a start.

 

Contaminated fuel can cause similar symptoms.

 

or possibly clogged fuel filter.
Also check TPS sweep.

 

P1135

 

Can that cause a misfire? I haven’t had time to look at anything else, I’m just starting a new job.

 

Do you notice any exhaust leaks?

 

If A/F sensor heater circuit bad not only will it cause bad MPG's as mentioned but can cause running problems due to sensor not heating up to correct temp and tricking pcm into thinking it's cold and adding more fuel.