911 SC cold start problem after new starter installed - coincidence?

[TJK]

My 911 SC would not crank after long hours of freeway driving until the starter cooled. Replaced the original starter at a shop with new High Torque Starter (Part# PEL-GE-STHT) from our host (which incidentally sounds very different!)
Next morning found the car very difficult to start - turns over fine, but takes several cranks to catch, coughs and sputters for a minute and then finally with some gas pedal feathering reaches idle. Then runs normally. Starts normally when warm.
Potentially another piece of the puzzle - a few days prior to starter swap, I started the car and it idled very rough, and was not drivable. Discovered the dome light fuse was fried, replaced that and all good thereafter - ran perfect, and no cold start issues; those arrived after the starter was swapped a few days later.
I Just replaced the oxygen sensor relay, thinking maybe that was going faulty and tripped the fuse, but didnt help with the cold start.
WUR or CSV the culprit and just a coincidence with the starter change? Related to the blowing of the oxygen sensor fuse?
Ideas appreciated.

[john walker's workshop]

I wonder if the yellow/blue wire is connected to the proper terminal on the solenoid. It activates the cold start valve.

[TJK]

Thanks for that tip - seems a likely candidate! I've had the car for >20 years and can't imagine that something else just packed it in the day the starter was changed...

[Glenfield]

Same condition TJK. Warm and hot start are fine but cold and warm cold takes a lot of cranking on a brand new high torque starter.

I’d put it down to fuel pressure and was going to check that this wknd. Thinking through it, that would more come into play with a warm hot start problem before CSV kicks in.

[fintstone]

I have the high torque on my 3.0 (SC engine) and it starts just fine when cold.

[SCadaddle]

Easiest method of determining if your oxygen sensor relay next to the Lambda CIS box under the passengers seat is working is to hold the relay in your fingers with one hand while you turn the key to start the car with the other hand. If it is working you'll feel the relay "thump" when it switches to make the contacts.