I just got my car back from the body shop (2007 corolla S manual transmission). Now it is ‘jumping’ while accelerating and also driving at a constant speed. It’s not drastic enough to move the needle on the accelerator or tachometer but I can feel it in my foot. It’s almost like a small hiccup that happens in all gears and all speeds. It doesn’t happen unless I’m in gear though (manual transmission, couldn’t feel anything while revving the engine in neutral) This happened when I first got the car. The problem went away when the starter and timing belt were replaced under warranty about 15,000 miles ago. I don’t know what they body shop could have done to cause this problem or what it is. The check engine light is not on, nor was it on the last time this happened. I’m very confused.
and now it stalls out. The engine just drops too low in the rpms and it stalls unless I catch it and rev the engine. It’s not consistent which is good but it also makes it hard to predict. Today it stalled out while braking, so before I got all the way down to a normal idle speed. I’m going to Carmax on Thursday but want to have an idea of whether this will be covered on my extended warranty or not. This seems bizarre at 49k miles.
Why was your car at a body shop? Is that really what you meant?
And why did you need a new timing belt at 15K miles?
More info …
I don’t know why they replaced the belt. I brought it in under warranty for it starting kinda slow and they replaced the starter and the timing belt. And to clarify I brought it in at 35k miles, which was 15k miles ago. I’m now at 50k miles, still low in mileage to be having problems.
It was at the body shop because my mother-in-law backed and turned too sharp and crunched the front right quarter panel. They did work on the body/frame, light, and brackets in there. Visual inspection looked fine after but it started acting up immediately and is getting worse. I put in a fuel injector cleaner the other day but it hasn’t done anything. I realize that could make it worse but it was already stalling out before I put that in there.
Take it back to the body shop or take it to a good local mechanic (you might need the latter). Explain the symptoms and ask them to please check the mounting, condition, and wiring for the crankshaft position sensor. It may have been damaged (or its wiring) either when the mother in law hit it and/or during the body work.
Would this sensor cause the check engine light to come on at some point? My light has not come on yet which I would assume narrows down some of the possibilities.
It would - but it doesn’t necessarily turn it on with every little weird thing - or it would probably be on all of the time for one random glitch or another. Most anything that would cause your “hiccups” would turn on the light. So whatever it is, it just isn’t bad enough right now to register an error code in the computer.
The thing about the CKP sensor is that it is exactly in the area of the timing belt and of the body damage/repair (the front of the engine which is on the front right of your car - the engine is in there sideways).
Good to know. I’ll try to find it myself tonight and see if there’s anything obvious. The mechanic at the body shop is going to check it out and see if it’s related to their repairs. This is the first option I’ve had that could be related so thank you! Hopefully that’s what it is, the insurance will then cover the cost and I won’t have to spend any extra money. 
I just got the call and it turned out to be a dirty throttle body. So at least it wasn’t fuel related and was sort of related to the sensor which couldn’t get clean air all the time. Thanks for the help!