EDIT: Problem is fixed! For me it was a huge vacuum leak in the form of a -no longer seated- egr tube running up into the manifold. Having to tap (and admittedly bang, lesson learned) on the egr valve had bent the bracket that holds the egr valve in place...this also dislodged the egr tube from the intake manifold so I removed it and carefully bent the bracket back the other way. Reinstalled and it's running and no codes! Now it just needs a tune up (which I'm giving it) so THANK YOU FOR ALL YOUR HELP EVERYONE







EDIT: I think I've discovered that after all the banging it took to get the egr valve off of the end of the exhaust, the bracket that holds the metal tube going from the back of the egr valve up into the intake manifold is out of wack and the tube is no longer seated...

Hi guys, long read...after this paragraph is a list of the stuff I've done. I have a 1995 4x2, 4.0 engine size, manual trans. Originally when the check engine light came on, autozone told me I needed a new egr valve. I couldn't find one but found an egr pressure sensor and replaced that and no more check engine light for almost a year. Check engine light came back on so I replaced egr pressure sensor again hoping for the best. No luck. So I replaced the egr valve itself but had to bang on it for two days with bolt blaster to get it off. Ever since it won't idle properly. For a couple days it would rev up super high then go low. Now it just dies as soon as I starts unless you keep it going while in neutral. Dangerously hard to drive and I don't want to damage the engine.

I replaced the egr valve again to make sure it wasn't faulty with no luck. Since I've replaced the idle control, throttle position sensor, throttle control, cleaned MAS (looked great), 2 of the o2 sensors down from the egr valve, fuel filter and the egr solenoid.

Just got a brake bleeder to test for vacuum leaks because I can't get it to stay running in order to do a water or propane test, and I'll be pulling the spark plugs and pcv valve to take a look tomorrow.

Am I on the right track?
problem fixed

 

Welcome to the forum

Leave the Vacuum hose off the EGR valve for now, plug the hose

Ford code list here: https://www.therangerstation.com/tec...II_codes.shtml

P0171 and P0174 mean the computer is having to open the fuel injectors longer than it calculated, doesn't mean engine is actually running Lean, just FYI

If you look at the list above and scroll down to P0400 you will see SOME of the possible EGR codes, there are more, lol
Point being the EXACT code is important, but so are the other codes the computer did NOT use
And as you can see there is no "replace EGR valve" code
Engine computers are not smart, they calculate air/fuel mix on the fly, that's all

And OBD2 coder readers are also NOT smart, if they were they would show you ALL the codes for a sensor when 1 code for that sensor is set

Stop changing sensors and controls, problem with new parts is they don't always work out of the box, YOU are the tester to see if they work, so..................grain of salt saying "well it can't be that its new", lol, 20 years ago that was true, but no more

Assuming no current codes, except EGR(if you have a smart phone you can get a Bluetooth OBD2 code reader, like ELM 327, for $15, good tool to have)
Check the vacuum hose on the FPR(fuel pressure regulator) its behind alternator on lower intake, has fuel return hose attached, if FPR leaks it sucks raw fuel in thru that vacuum line, so if there is gasoline in that line FPR is leaking

IAC Valve, air control valve, this is what the computer uses to keep engine at idle, its a 12volt solenoid, can only be replaced with Motorcraft or Hitachi brands, other brands won't work on Ford system
Better to get a use motorcraft at wrecking yard than new any other brand

If you have a vacuum leak idle would stay high unless it one BIG leak, like PCV or Brake booster

Low fuel pressure will set Lean codes, there is no fuel pressure sensor, computer assume 35psi at each injector, if its 20psi then Lean codes because not enough fuel is flowing out when injector is open

Clogged exhaust, also sets lean codes but engine should idle OK, and then stumble when raising RPMs as exhaust pressure backs up

If you have other codes let us know, exact codes, not I think it was....................

 

Are those your current codes, or the ones from a year ago?

 

P0171 and P0174 are current codes. Never was given a code by autozone originally, just told what I needed. Was less informed then than I was yesterday, and was way less informed yesterday than I am today. Thanks for the info! I'll get on that.