ECU Coolant Sensor issues? (1998 Mustang GT 4.6L)

[Sn95.Draconis-Kev]

I have had hot start issues with my Mustang for the longest time and i got a tip from a friend that it ought be the coolant sensor going to the ECU.
I knew that I had one on the left side of the coolant overpass tube on the front of the engine. I bought a OEM sensor and replaced it (sensor looked different which was odd to me but the connector still fit.) then my dashboard coolant temp gauge stopped working and i still had hot start issues.. So I put the old one back in and it was working again.

Did some more info digging and found out that it has two sensors. I removed the second one (right side of the overpass tube) and it was identical to the new one I ordered. So I out it in and now my hot start issues are gone! All good right? Not really. Now I have cold start issues.

Basically it takes about 5-10 seconds of cranking to start and it starts sluggish for a few seconds before it runs normally. This has always been the problem on hot starts until I changed that sensor. Now it has the exact same issue on cold starts, but not on hot starts.

Help?

 

[96blak54]

WOW
I dont know how to respond to this or offer any feasible info to help.

Definitely go over all vacuum lines and soft parts/hoses,....could have cracks. Then I would point to injector servicing, making sure spray atomizing. Then maybe oxygen sensors? The more I learn about degraded working oxygen sensors, the more I hate fuel injection.

 

[Sn95.Draconis-Kev]

WOW
I dont know how to respond to this or offer any feasible info to help.

Definitely go over all vacuum lines and soft parts/hoses,....could have cracks. Then I would point to injector servicing, making sure spray atomizing. Then maybe oxygen sensors? The more I learn about degraded working oxygen sensors, the more I hate fuel injection.

I've replaced some cracked vacuum hoses, and rebuild the injectors a couple of weeks ago.
She runs fine otherwise it's just the hit start. I've also cleaned the throttle body, IAC valve and EGR valve.

Do you have an idea where I can find the oxygen sensor? Or do you mean the MAF?