hey everyone,
figured this would be a good place to try and figure out the ghost in my car.
i have a 01 monte carlo with the 3400 engine, 158,000 miles.

When doing about 70mph on the freeway you can see the rpm needle almost shake between 1900 and 2300 rpms. when it does this jumping of the rpms you can feel the car jump back and forth as if the car was running out of gas, but i have checked and there doesnt seem to be a fuel issue.

when driving in the city , at random will have the rpm jumping feeling again, jittering of rpms, and few and random, it will stall and start back up right away just fine.

Trying to get somewhat of a idea without having to take it from garage to garage, please help if you have any knowledge of this issue,
thanks

 

Without actually experiencing it first hand...

Whens the last time it had a tune-up? That would be my first thought with all those miles on it...

I would also consider doing a Oil change on it....

You could also possibly consider a clogged/plugged up catalytic converter..

Hope this helps!

 

i get the oil changes done early , tune up is about to be underway, i found a post on here from almost 2 years ago with exactly the same issues but the thread just stops after a while.

if i rev it to 2000/ hwy rpm in neutral it holds the rpms steady, only does this in gear, praying it has nothing to do with my trans.

 

Reving the motor in neutral really doesn't prove or disprove anything...IMO

Its acting up under a load (driving) Which makes me also lean towards a clogged catalytic converter...

Whens the last time you did a fluid filter change on the transmission?

 

havent before , just got it 4 months ago, previous owner took pretty good care of it , and i have never dealt with this kind of a issue before so i am lost on where to check , going to do the tune up today, as for if that doesnt fix it, then no clue.

 

Just take it one step at a time...

Let us know if the tune-up resolved the issue.

 

Had similar issue. The insides of my cat fell apart. Replaced the cat and all is well.

 

Reading the symptoms, if the car is still on factory plugs, you are beyond the mileage they were expected to survive. Change plugs and wires, you probably have a very light mis-firing. Use AC Delco or NGK plugs, DO NOT USE BOSCH PLUGS!
Also, consider getting your fuel filter changed too. Odds are it's been neglected and could use a fresh filter.

Also, make sure you are not throwing any engine codes. If you are, start with that first before doing anything.

 

Pcv valve?