Ok so had this issue come up last summer but things cooled down before I was able to figure this issue out and wasn't able to replicate the issue until summer came back around.

So here's the issue. In the summer (or any day that is above 75 but it gets worse with more heat) once the engine is up to temp and I've been driving around for a while while in the rpm range of 1,200 to about 1,800 if I start climbing a hill or accelerating slowly without causing the trans to downshift the RPM's will start to bounce or jump around which is noticeable to everyone in the car as the jumps become more frequent or larger than a few hundred RPM (I notice even slight jumps because I drive it and know its not normal). The issue is even more noticeable in town between the speeds of 35-45mph so I am actively avoiding those speeds or having to force 3rd gear to stay outside the range when I do so it doesn't drive me nuts.

Additional info would be that I've replicated this in 3rd gear (same RPM range) on even hotter days but its harder than to get the issue to appear than in 4th. Also I can get this issue to arise on cooler days if I'm driving long distance. So I assume this is link to temperature of something in some way. All the fluids are at their appropriate levels and none look dirty (Trans, coolant, steering, ect)

I've attached two video from two separate days, each while using a constant throttle input, the jumps you see are purely from the issue described above. Both climbing two different slight hills which normally wouldn't require downshifting to make it up. This is an auto trans original to the vehicle. Otherwise runs like a dream other than in that range with a slight load. Any advice or guidance is much appreciated.


https://www.youtube.com/watch?v=c3vl...ature=youtu.be

https://www.youtube.com/watch?v=VbyE...ature=youtu.be

 

So I've gone about changing the fuel filter, cleaning the MAF sensor and the throttle body. Unfortunately those things have not helped the issue any which from my reading were the places to start with.

I'm at a loss of what to do next. I would appreciate some help on this.

Here is another video from today after those changes. Agin constant pedal pressure, and a slight incline. https://www.youtube.com/watch?v=de6U...ature=youtu.be

https://www.youtube.com/watch?v=de6U...ature=youtu.be

 

usually climbing a hill or under load indicate a skip or misfire. Could be bad wire, cap or rotor, plug. My truck did this once, took me 2 weeks throwing parts at and found a slightly loose plug. Would be tight enough while cold but once warmed up the block expanded enough to loosen it up. Also could be a pump issue.

 

Logical idea, guess I'll start checking those. I didn't even consider a skip or misfire since she runs so smooth in all other conditions.

I ruled out the fuel pump using the guide that the Captain posts. Pressures are within acceptable levels.

Thanks for the tips, I'll start checking those. Anything else anyone can add is appreciated. I'll keep progress posted, though might not get to too much until Friday or Saturday