I will explain best I can. I am not a shark at this subject. So I lost my dad to cancer in 2016 he gave me a f150 2003 4.2L . It’s very high in my miles over 300thousand but it was running very until now. I was told it has to blown valves in the head. I have tried fixing a lot of things my self like injectors oxygen sensor fuel pump. But can’t seem to locate the problem. It will fire right up but I have to give it gas to make it stay on. I have drove it in this shape but it has rough and tough ride. Shaking and bucking until passed 2rpm then smoothies out a bit idle high at take off not over heating and no oil mix how can I figure out the problem or is time to put my dads truck to rest. Please help I’m having a baby next month and it’s my only transportation.

  • Welcome to Motor Vehicle Maintenance & Repair! – Pᴀᴜʟsᴛᴇʀ2 Dec 14 '18 at 12:30
  • Sound like this ol truck needs a makeover :) your pressing on the gas issue is because your 02 sensor sees too much air, either because the fuels psi isn't high and stable or because there's an air leak, but you could also have a bad PCV, MAP, MAF, Idle control sensor that's malfunctioning – user38183 Dec 14 '18 at 12:39

As has been said, syptoms are a vacuum leak-if you can get a scanner, see if the fuel trims improve when you rev it. Ideally use a smoke machine in the inlet to see if you can find any leaks, or spray propane around all vacuum lines/inlet manifold joints

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