Hi
I have been trying to fix my truck with no luck, problem is that when is idling the rpm's would go crazy to the point that it seems the motor would stall and when i drive it feels rough.
My truck is an 88 f150 4.9 L6, 4 speeds and i have replaced the following:
EGR
PCV
IACV
TPS
INTAKE GASKET
MAP SENSOR And i even replaced the ECU with a same number ecu i found on ebay, So o don't know what else to do. The only thing i haven't tried is replacing the throttle body gasket.
Please help.

I am posting a link to a video i uploaded so you guys could see the problem.


F150 4.9 L6 crazy rpm's:

 

Seems like the ECU could be parameter hunting. How long has it been since a fuel filter change? If there is a restriction in fuel supply, the ECM will automatically adjust air intake, fuel injection timing and spark plug timing to get everything back in line.

 

Fuel filter was replaced probably at around 10,000 miles ago.

 

I bet there is an air leak in the intake area.

Check for air/vacuum leaks before spending more money.

 

I just replaced the upper intake manifold gasket, only thing i didn't replaced was the throttle body gasket.

 

have you checked for codes?

 

Yes both koeo and koer and i might be mistaking but in Koeo mode i got 23 and 67 and in koer i got 12, 23, 13 and 77.
KOEO: KOER:

 

check the throttel body gasket and take a good look at the air idel solinoid.

 

I would check those things. I am honestly about to give up.

 

Your TPS is still screwed up in my opinion....Test it or replace it again. Part 1 -Throttle Position Sensor (TPS) Test (Ford 5.0L, 5.8L)

Spray some carb cleaner around your throttle body gasket as its running see if your getting leak. Engine should rev up higher.


Update 4.9L: http://troubleshootmyvehicle.com/for...test-the-tps-1

 

I will try that. Thanks for the link.