93 4.0 Ranger runs like dog crap

[RALLIART15]

I have a 93 4.0 Ranger, 183,x.. miles.
List of new parts between me and last owner,
MAF, TPS, O2, FILTERS, plugs, wires, coil.. sure I'm missing some
KOEO
172 right rich
173 right lean
176 left rich
177 left lean
KOER
411 idle high
412 idle low
Fuel pressure tested ok KOEO & KOER (don't remember exact numbers but was towards the low side)
Now for the confusing part, truck is in Sacramento elevation 35' runs like crap, surges, rough idle, 10mpg, garbage garbage garbage.
Went to OR last weekend elevation 3500' ran amazing, minimal surge barely noticeable, 16.9mpg thru 2 tanks full to empty, first tank took 16, second took 14.5 so I used most the tank..

Bought it here in Sac, drove it to OR for a week at my parents, starting getting good as I climbed Shasta Northbound and ran great from there on North. On the way back it ran great from Redmond, OR to south side of shasta. First tank thru it was 16+mpg then after shasta next half tank was 13 then last tank into sacramento was 10.. seems the redding shasta area is where it went bad to good and back.

Drives like dogshit again, no smoke but rich enough my bumper and bed are black..

SO... if anyone has any ideas please I am all ears....

 

[RALLIART15]

Only things left to replace are ECM and Injectors
By dogshit I mean at WOT runs ok and accelerates slightly, under WOT 95%ish doesn't have power to maintain speed so I have to floor it-let up-floor it-let up..... not pleasant.

 

[MrShorty]

For something running rich like that, I think the first thing I'd check would be the fuel system. Pull the vacuum line off of the fuel pressure regulator and check for gas (gas in that vacuum line means bad FPR). Then put a fuel pressure gauge on it and see if the fuel pressure is correct.

 

[RALLIART15]

Thank you for the input but as stated above fuel system has been tested and is in good working order.

 

[RALLIART15]

bump.......

 

[FIND]

What kind of dog?


Exhaust leaks on the manifold would be my first guess. Test your injectors and test compression next.

 

[RALLIART15]

A broken dog..
Good thought on manifolds. No audible leak but doesn't mean it isn't there.
Injector test is also a good idea but I can't believe that there is an intermittent failure that is so specific to location...

 

[RALLIART15]

No found leaks and injector pulse is good.

 

[scoty]

Just a guess but could it be to do with the air as in when your lower down its strugling for air and higher altitude it runs better which would mean your starving it of air higher up.but should run ok when lower down which dont make sence but i would be looking at the air mixture side to be honest ...