My friend says he's tried askin at TCstangs but no one gave him an answer on what it could be. Anywas he has a 1995(maybe 94) GT 5.0 mustang with basic mods, intakem, exhuast, underdrive pulleys etc..

A few weeks ago he went and changed out most of the ignition stuff, wires, plugs, distrbuter thing, and it ran fine for a day or two, but now the car stumbles/backfires.

From what I've seen if you sit in netrual and try revving it, it will rev up to ~4k and then it starts to stumble and backfire and it can't go any higher, I guess this is how it acts also while driving.

I know this is a DSM board but, any ideas?

Probably incorrectly gapped plugs or just shitty replacement plugs/wires in general

I told him to check the gap and firing order and he said it was all good, I'll probably just have him stop by and check it all myself.

I suppose it is possible its something else, and it coincidently happened after doing a tune-up.

It sounds like spart either way I think.

If all eles is correct from what eveyone eles has posted, Maybe watch TPS voltage too see any unwanted Flex in that.

BTW. Any DTC's?

yes, but I think he said that checker said it was EGR

Did this DTC show up at the same time the Cars current problem did or was this light just put off for awhile

Around the same time I think, he said he brought it to the dealer but they didn't know what it was

No DTCs at the moment, Ill post a vid in a sec

Not sure if you already said this, but does this Miss/orStumble issue seem to be Evan, or does it seem to get a little worse when driving it underload, rather then just reving it up.

Yes it does, it will creep up to redline but its slow and sounds all rumbly imho

Here is a video, you need quicktime to view it I think

Mustang video