Wouldn't a compression issue be all the time and not just after sitting a couple days? Unless it makes good compression just on consecutive days it is a DD?
I thought regulator also but I've been riding around for 2 days with a fuel pressure gauge sticking out the hood, everything seems normal. No, I only drive it on the weekends. I usually crank it up every couple of days or I might drive it to the store by the house during the week.
that is screwed up the PCM ECM will not give a code. I may be wrong but I'm banking on it being the IAC. Remove the IAC from it's housing. Turn the ignition key to "On" but do not start the engine. Observe the IAC. If the valve moves in and out, the IAC is good. If it does nothing, replace the unit and try again.
I'll pull it tomorrow and try. I don't think that's it. It idles perfect. What makes you think IAC Joe?
Seems you've hit all the other areas without codes popping up. The watching the IAC valve motor action is cheaper than trying to replace another $ eating part that doesn't cure it. From what I've priced those IAC arent cheap on a 4.6 There is a resistance check across the terminals of the IAC also but I'm having trouble finding the exact value it should read for your year and model. Anything above 10,000 ohm should be bad and some have a diode across the motor windings which make it polarized or appear to be an open circuit measured one way and low resistance if swapping the terminals tested. The hard starting was a symptom the the wife's Mazda went thru. It would idle fine after that. Then it started dieing at red lights, high idle, no idle, no codes and pressure differential codes. That was the second IAC I've had to put on it in 97K.
