help air intrusion i think

ok so it started out with a really high idle i dont know how high because my tach dont work but it sounded around 1500-2k rpms...
i was just driving along and the next stop it was like the throttle was stuck.. so i pulled over throttle was closed and still high idle..
so i was driving to my dads at that time figured i would look at it when i got there, got to his place only thing i could get the idle to come down was to turn the idle screw 2-3 turns out... truck seemed fine other then maybe a little under powered...
drove it for another 2 day decided to change the fuel filter its been a while, did so truck ran great after.. but i didnt test drive it,


got in it today to drive to work..
fires up great get driving and the power still felt down some... get about 1/2 way to work from a 8mile drive it looses all guts and wot was about 2k rpms now and i couldnt pick up speed grey smoke out the tail pipe, well im a mechanic but new to diesels so i shut it off decide to pull it in the back to take a look fired right up ran fine.... shut it off wont fire back up but cranks..

long story shot i bleed the fuel system fires up. parked it back out front... at lunch test started fires right up......
time to leave 4 hours later lost prime wouldnt fire.... re-primed fires up and felt fine for the whole drive back home.. stopped and got some fuel cuz i was low so it even added more time to the drive..

things ive already replaced in the recent past
fuel pump (not airtex) year and half ago
selector valve removed had issues before same time i replaced fuel pump
new filter (fram not my favorite) changed yesterday
and return lines and orings about 2-3years ago


so im sure im sucking air guess its a figure out where game.. but any suggestion on the high idle before this showed up.. im wondering do i have somehting else going on like maybe a dieing injector pump... mileage is unknown on this motor and pump

if i had an electric fuel pump would this mask my issue?

I had a similar issue. It was leaking and bleeding off. Turns out the starter was weak. Cleaned the terminals and put a good starter in her and she started every time. Sometimes still hard to start, but would. I then replaced the return lines and now runs great. I did the return lines for the first time and it took me about an hour. Just make sure you lube the o rings up. There are some good writeups here. I bought a return kit for about 40 bucks from napa. I also got extra line and replaced all rubber fuel hoses. Hope that helps.

im stuck at...

73idi88f350 said:

truck ran great after.. but i didnt test drive it,

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