Fuel supply issue?

[rzr6-4]

09 2500 5.7, 87 octane fuel, I've had issues since I got it where at times it would have an issues with low end torque and occasional sputtering on acceleration, and it seems like its worse when its cold. It seems to be slowly getting worse and particularly the last few weeks where morning temps have gone from 60-70 to 30-50. A few months ago it wasn't terrible as I could drive normally most of the time but now it is borderline undrivable unless I but it in OD OFF, locking it into 4th. If I get on it from the start it is usually fine but going down the highway it has no power at all below 2500-3000rpm, and struggles to stay in 6th on flat ground, much less up hill which is why I have to lock it out so its not constantly shifting. Always starts and idles fine.

I've noticed it before but I finally got it to do it really well a couple days ago. Cool morning, engine was still cold, and the road I was on transitioned from a 35 to a 55 so I was slowly speeding up. All the sudden it bogged down and didn't want to accelerate. I did this for a few seconds, just holding speed with an odd sputtering engine note. Then I gave it a little more gas, not enough to downshift. When I gave it more gas, it slowed down even more. In my mind it was like by opening the throttle I gave it more air but it didn't get any more fuel so it engine braked back down. When it sputters I would describe the feeling as like when you are running out of gas.

Is my thinking correct, or at least seem plausible? I have a code reader I can plug in but I didn't know if that would help read fuel pressure, and if it does then what pressure to expect. What all should I check for?

Current engine codes are the gascap code that everyone seems to get but I can't remember the number and one code each side for my bluetooth cats.

 

[rzr6-4]

bump

 

[Dean2]

If your gas cap is not making a good seal you get the code. Fix the gas cap first as the system is designed to operate properly sealed. Very likely as the seal got worse your stumble go worse. Next toss in a good fuel system cleaner. Once you get those two done come back and report progress. Start simple work up, way to many things it could be to give better advice with the paucity of diagnostic info provided.

 

[rzr6-4]

If your gas cap is not making a good seal you get the code. Fix the gas cap first as the system is designed to operate properly sealed. Very likely as the seal got worse your stumble go worse. Next toss in a good fuel system cleaner. Once you get those two done come back and report progress. Start simple work up, way to many things it could be to give better advice with the paucity of diagnostic info provided.

New gas cap and several bottles of fuel system treatment did little to nothing. One of the hoses on the evap canister was loose so I put a hose clamp on that yesterday but its still doing it.

 

[Dean2]

Okay, so next step is to measure fuel pressure at the rail where it goes to the injectors as well as fuel mix at various throttle positions while driving. That will tell you if it is fuel or something else. It is possible it is electrical, are you sure your battery is good. Have you done a proper load test and checked all grounds and connections for corrosion and tightnesss.