Hi Jordan,
Just to clarify, did you change these to address this issue or has this issue started since you replaced one of those items you mentioned.
If the mileage is correct in this post, I assume you changed the engine and trans because of the mileage and then the pump and filter to try and address the sputter.
If this is only occurring during idle at cold start, then there is a good chance that it is the idle air control valve. The IAC is PCM controlled and regulates the air going into the engine during idle. If you take off immediately and it does not do this, then that would support this theory. These are easily cleaned. Just remove it and clean it out with carb cleaner.
The other idea I had was a possible oxygen sensor however, the PCM is usually not using these sensors to run the engine until after it warms up.
If the IAC does not turn out to be the issue, I would be interested in seeing what the spark plugs look like. If you can, take a picture of the plug electrodes and send them in so we can see what the engine is doing.
Here is a link to some other ideas about surging engines. Let me know what you find and we can dig deeper.
https://www.2carpros.com/articles/engine-surges
Images (Click to enlarge)
Apr 12, 2019 at 2:47 PM
