WTF surging and cutting out under load

[Lazy_C_Ranch]

sorry i posted this in the wrong forum....GRRRRR

2005 F350, auto transmission, dually 4x4
163K miles
Not sure what's going on but ever since I had the head gaskets replaced, the egr and oil cooler replaced and the installation of a block off plate in the up-pipe, when I get the truck to about 2200 rpms under load, it starts cutting out and acting like it's hitting a brick wall.
Cruising at that speed, usually around 65 to 70 miles an hour, it's okay but begins the cutting out trying to get up a hill or accelerating.
Anyone know what's up with this? I had the latest ECM flash done in April after the head gaskets were replaced so I would think I'd be okay?

HELP! I'm going TDY for a few weeks and would like to resolve this issue upon my return

[DryHeatDude03]

Do you still have the original STC fitting?,, sounds like it could be a high pressure oil issue, or bad IPR valve. Any hard start issues?,, any smoke? any codes pulled?

[Lazy_C_Ranch]

Originally Posted by DryHeatDude03

Do you still have the original STC fitting?,, sounds like it could be a high pressure oil issue, or bad IPR valve. Any hard start issues?,, any smoke? any codes pulled?

Those are good questions. I don't know the answers to all of them but there is no smoke, no cel and I haven't checked for codes.
Checking any of that looks like I might as well replace the stuff related to the hpop correct??

[bismic]

Originally Posted by DryHeatDude03

Do you still have the original STC fitting?,, sounds like it could be a high pressure oil issue, or bad IPR valve. Any hard start issues?,, any smoke? any codes pulled?

It could also be the ICP sensor, but the IPR or STC fitting leak are probably more likely candidates.

[DryHeatDude03]

Originally Posted by Lazy_C_Ranch

Those are good questions. I don't know the answers to all of them but there is no smoke, no cel and I haven't checked for codes.
Checking any of that looks like I might as well replace the stuff related to the hpop correct??

Don't just start throwing parts at the truck, that can get needlessly expensive in short order. You need to get the truck on a good scan tool such as AE, and check for any codes that may/or may not be present, and also check ICP and IPR duty cycle. It could be a number of different things based on the info presented. But without more info its throwing darts in the dark.

[DryHeatDude03]

Originally Posted by bismic

It could also be the ICP sensor, but the IPR or STC fitting leak are probably more likely candidates.

Agreed,,

[bismic]

Originally Posted by DryHeatDude03

Don't just start throwing parts at the truck, that can get needlessly expensive in short order. You need to get the truck on a good scan tool such as AE, and check for any codes that may/or may not be present, and also check ICP and IPR duty cycle. It could be a number of different things based on the info presented. But without more info its throwing darts in the dark.

This is some of the best advice on the internet!!