Cranks then tries to shut off

So now, most of the time when I start the engine, it kind of sputters like it is going to cut off, then idles up to normal after a few seconds. I've been chasing a surging type gremlin for weeks and I'm wondering if the 2 are related. I've thought: dirty filter and intake, cleaned, bad tps, after cleaning intake, hasn't happened, and now I'm wondering about the cps. I'm thinking cps since when they die, you don't crank. Maybe it has been going down for a while and now it is almost shot. Any thoughts are greatly appreciated.

btt

What year is it? Blocked cat maybe.

99 This just started 2 days ago, if that helps.

Does it take a long time to crank?

About a month ago I was dealing with this, and it came out of no where, and I also have a 99. It would take a long time of cranking before it would fire (No matter how long I let the pump run before I begain cranking it). Once it caught, it would run rough for about 5-7 seconds, then smooth out and be good to go. It only did it on a cold start, mainly after it sat overnight.

After about 4 days, right as I had it down to a science as to when it was going to act up, it went away. The long crank time still comes and goes....mainly comes though, but it hasn't started the running rough crap.

Does this sound like what yours is doing?

Yes! Sounds like it. I had a buddy that races Mustangs think about it and he thought IAC. I changed it out tonight and am interested to see what happens in the morning. The tube, as I call it, coming off the tb and down to the sensor was kind of nasty, so it got a cleaning.

Let me know your results. This weekend I am planning on pulling a couple of sensors off and cleaning/inspecting them....as this long cranking is getting quite annoying.

The funny thing is, once it's warmed up, it'll fire right up.

This morning, it cranked right up. So far, I've got a 1yr old tps, new iac sensor, and a CLEAN throttle body. Make sure that you clean out the iac "tube".

Yeah, I've got a 3 MONTH old TPS, and a clean TB. Looks like i'll be pulling some more sensors off this weekend for a good cleaning!