I have wrenched on cars for 15 years as a hobby.

That being said i dont know everything about cars so maybe yall can help a fella out.

I just rebuilt the power train and overhauled the engine of my 2002 ford mustang base model convertible 3.8L V6 due to it failing its last emissions test as well as having abrupt periodic power loss/accelerator lag even with the accelerator buried to the floor. (This would happen on flat stretches or hills it didnt seem to matter)

So i replaced the egr valve and the egr pressure sensor as well as the egr solenoid plus the ignition coil pack and spark cables and spark plugs as well as doing an oil change and replacing the air filter plus the fuel pump and fuel filter plus the injectors and the accelerator cable plus the exhaust headers and exhaust system with catalytic converters and muffler.
Then because i was already so far into her i went and replaced her brakes and rotors and shocks plus abs sensors as well as tires and wiper blades plus the fuses and battery etc etc then got her an alignment and did a compression test.(no loss). as well as another obd scan from my bosch 3100 obd ll reader.(no codes or dtc's)

Well she passed emissions and was acting like she was brand new for a few days but then out of the blue she starts up with the same problems that led to the rebuild.....

Thoughts anyone?

 

Do you think you might be able to provide the codes you might have received prior to all the work you did?
Present codes also if any?

 

Original Codes before rebuild
p0300
P0301
P0302
P0303
Same codes are presenting now after rebuild.

Truth be told im flummoxed as to how to solve this problem at this point....

 

The P0300 tells you that the computer is seeing an RPM difference between the Cam and Crank sensor. As you know, the P0301, 302 & 303 are your misfires for cylinder 1-3. Does the engine act like cylinders 1-3 are misfiring or does it run smooth?. If smooth, I would start by looking at the connectors for the can and crank sensors along with the wiring right at the connectors for any bad/burnt connections.

 

it runs smooth and timing light tests show no misfire....hadnt thought about the cam and crank sensors though....ill check those in the morning

 

Replaced crank shaft positioning sensor.
the others were good.
still getting the same codes.....

 

Fuel pressure/volume checked after replacements?
EGR supply disconnected, still randoms set? or EGR related generated..
CMP checked, how?