I bought a 1990 ranger 4.0 v6 4x4 that has a 95 4.0 explorer engine in it. Over the last month I have had surging and power loss issues after the engine is warmed up.
Shows no codes on ignition only test but when I did the engine running test it only read 4 cylinders no codes. On the way to the shop today doing same surging and powert loss. Got there and had a mechanic ride with me and it ran perfect. Went home and ran the engine running test again and it now reads 6 cylinders no codes.
Using a Innova Digital Code Reader
No misfireing and Idles normally
Any and all help greatly appriciated!!


New items installed

BBK Trottle Body
Transmission
Alternator and connector
MAF and connector
TPS and connector
Idle control module
Engine air temp sensor
fuel pump
fuel pressure regulator
fuel filter
plugs (motorcraft)
plug wires

 

Welcome to the forum

Hard to tell with all the "new" parts
"New" used to mean "tested and working"
"New" now means "you test it for us and we'll replace it if it didn't work", lol

So a bit of a Potluck on which of the "new" ones might be bad out of the box, lol.

After engine is warmed up it should idle at about 625rpm with manual trans or 750 with automatic
With engine warm and idling unplug the 2 wires on the IAC Valve(Idle control module), it will close all the way and RPMs should drop to 500 or engine may even stall, either is good it means no vacuum leaks
If idle stays high you have a vacuum leak


The air tube from MAF sensor to intake needs to be air tight, check it for cracks or loose fit, a leak here is the same as vacuum leak as far as MAF and computer are concerned.

A $25 vacuum gauge can tell you ALOT about a gasoline engine.
No matter what "they" add to the outside a gas engine is still just an air pump, self powered, but still just an air pump.
And best way to test a pump is by looking at its pressure
Good read here on what different pressures mean: Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine

 

Thank you for the info!!
Ill stop at the parts store and get a vacuum gage and check the things you mentioned and the Technical Article.
Again thanks for the help!! RonD