(1997 7.3 F350 auto) This is going to be a long one but bear with me guys cause im about 2 lope starts away from crushing this truck. So for a while there on cold starts my truck would what sounded like a misfire, i mean shake at idle, choppy when driving it, no power, and this was even after letting it idle and warm up. And if i got on it down a county road it was like someone flipped a switch and it would run great and smooth. Also on start ups sometimes it would fire and lope once or twice and others it wouldnt lope. Well now I just put injectors, gp’s, gp relay, valve cover gaskets with the built in harness so no clip on the inside. (Wayy more power than before)And now its got a choppy idle, and accelerating after stopping it would hesitate like twice and then put you back in your seat and i’d be hauling a**. Also when i start it it doesnt fire like it should, its like a couple second crank time that eases into the truck firing and then lopes hard until I hold 1,000 rpm and let off. But then this morning i fired it up same thing but it was kind of choppy and very low power, i cleaned the return screen and was on my way to get a fuel filter and again, like a switch it started running amazing, set me back in my seat and i was doing 70 in no time. But still had that choppy idle, and hesitates after stop. I checked fuel pressure at idle it bouces between 50-55 i cant test it under load cause my guage is too short. I pulled out the fuel bowl a little time back to clean it and a lot of ***** came out like black gunk maybe even some sand. Ive been religiously changing filters and cleaning the return screen, oil changes every 3000 miles, zero oil leaks so the oil isnt low (Yes i checked) i just dropped the rear tank and cleaned it, ran a few bottles of bio clean, diesel clear, and always use power services fuel additive, nothing changed after cleaning either of them out. The lines from the pump to the bowl are fine, no fuel in valley. Brand new ICP, IPR, EBPV sensor, Oil pressure sensor, EBPV hard line, CPS. Im lost here guys please help before I scrap this thing haha. No chips, no tuners, the truck is stock as it gets except the intake. Im assuming my problem is electrical as the way it runs changes in a split second. Like someone flipped a switch.

No codes, fuel pressure at fuel bowl off the schrader valve is at 50-55 even when I rev it up (in neutral cause i can drive with the hood up as my gauge is too short to reach) but even at 2000 rpm in neutral it stays right at 50-55 psi I did see it drop a tad once or twice when i did it.

Try plugging in the block heater overnight and see how it starts in the morning. What you are describing sounds like worn injectors. If armature clearance is to low the injector will not start firing until the oil gets heated up and thins out.

The temperature doesnt matter. I could let the truck get to operating temp and itll still do it but when driving itll just all of a sudden stop. I tried plugging it in last night. I usually do every night cause i live in Colorado.

Nope. Back pressure valve is not stuck. I wish it was that easy. Trust me i know what it is haha, I have it on a switch right now in the cab so i can choose when it comes on haha.

So am I. But i mean brand new gp’s and plugging it in it should be fine in that area.

I would pull the injector solenoids and measure armature clearance. You want .002-.004. Anything below .002 is a bad injector.

Sounds good. Only problem I have with that is that it did it with my old injectors and now with the new ones too.

This morning it did something weird when trying to start it. I would crank it and it would fire and then shut off right after one lope. So I had to keep on the key and give it some throttle to keep it running. And then same thing, had about half the power, kind of shakey going down the road and then just before I got to work again like a switch it ran smooth when driving and had a choppy idle. Also if im cruising and depress the accelerator maybe an inch jut to keep speed it will surge, feels like im driving on washboard.

Have you checked the uvch?

You may have a throttle position sensor issue. If it is sending erractic voltage it can cause some weird problems. I don’t have it at hand, but you can test it.