running issues

[strokers]

I have been having a running issue that has been getting worse and now getting to point my truck has become undriveable.
What I have mustang efi , Ron francis/rjm harness and a centech body harness Vintage aire magnum.

it started to miss and cut out a few months ago when I had ac on and fan on high and was putting engine under a heavy load. I could keep it from cutting out by turning the fan down Or I was to let up on accelerator the truck would run fine. Yesterday I took truck out and drove it about 10 miles it started doing it again this time without any fan on and light throttle.
I had reset the ecm previous to taking it out to see if it would solve the problem. after taking it out now only codes I get is 15 koeo. Which is kam failure from resetting ecm I believe.

I have the feeling it is a power or ground issue to ecm I checked the wiring for rjm harness ground on back of engine. The dedicated ground for the air.

It is almost like the ecm resets I am going to take it to work tomorrow and figure out if there are any other hints. I almost believe the check engine light flashes when it does miss/cutout.

 

[Viperwolf1]

Check fuel pressure.

 

[strokers]

Check fuel pressure.

I will check it tomorrow at work. I haven't checked it yet because it will run fine for the the first 10 miles or so and wasn't sure how to check fuel pressure while it started having trouble without adding a guage

 

[WheelHorse]

Alternator keeping up with low rpm and high fan w/AC on?

You had mentioned putting (low rpm) and AC and high fan speed (high electrical loads).

 

[carmi]

Check Plugs and Wires. Had similar problems with spark plugs that were worn and gapped to much. Although, it was also pretty temperamental at starting. Check engine in a dark location while it's running. Often times you can see if the wires are arcing. Check fuel filter. A dirty filter will often allow the engine to run for a while until the demand exceeds the available restricted flow.

 

[strokers]

I ordered a fuel pressure guage waiting on it to show up so I can test. I check spark plugs and wires for any spots that didn't look good. I have efi and am unsure on filter waiting on guage setup so I can tell.

I am unsure if it is keeping up with high load low rpm. My volt guage never gets below 13v even at idle with all electrics on.