The RX5.0 has developed a problem while sitting around and getting Hot Rodded, not I am driving it more I am finding a big stumble under hard acceleration, it starts missing, like an electrical break down, then just goes away like it was never there.
Today I felt a mild stumble under very gentle conditions.
My first thought is the used MAF, that has sat around for a couple of years, is acting up, but have you guys got any other ideas.
Thanks
Ignition system? Bad coil or plug wires can do that, especially if they're grounding to something that flops around, like a hose.
Seems to be too irregular to be ignition, and I have good plugs, wires, MSD distributor and MSD coil with stock (reprogrammed) 9AL computer.
Of course this is all guesswork at this time
i had a 5.0 crown vic that had a bad fuel pressure regulator that had similar symptoms
MSD ignition stuff is hit-or-miss, so I'd try swapping that out for something else before digging into it much further...
check all grounds. i had one where i routed the wiring harness poorly, and when the engine twisted on the mounts on a hard launch, it would ground out the coil B+. took a while to find that, LOL.
MSD = My Spark Disappeared! 
I've had lots of OEM electronic ignition modules provide intermittent weak spark. A new igniter always fixed the problem.
TFI module? Sounds somewhat like what mine was doing when it died.
I was told to scout out a vacuum leak on my 95 5.0 with very similar symptoms. Haven't had the chance to do that yet. Mine wasn't lighting the CEL so it may well be just that.
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