My car has been running great since getting the fuel pump replaced, correct fuel filter swapped, and new line installed as well as fixing the diff tube back in place, but you know how that doesn't last long with these beasts sometimes it's just one of them months lol.

I still have a faulty Air Conditioner Relay, the unique white one above the front left underside cover so I have to take the 2, 30 amp fuses out at nearly every stop when it's hot out so that the fans don't stay runnin and drain my battery however sometimes the fans stay off til I walk inside and have been long gone so my battery died this week again.
So I went to jump the car but I also have been tight on funds for a little while due to a sick dad and expenses going up bills and such, so I have a really sh%tty cheap jump pack, talkin like $30 on amazon. Basically that jump pack gives me like a truly 5 second window to hit the boost button, jump the car, run to the drivers seat and crank the engine and it would cut out mid crank... about 4 times and I was late to a window tint consultation appointment for it and needed to get her started, so I did til I did. Got some whirring from the last few cranks, not a great sound, along with squeaking of some belt or pulley or harmonic balancer. I assume that may be the alternator belt from excess jumps sent to the car over and over, or maybe it can slip or something??? I then revved it a little and the squeak would get slightly worst til getting to a point and silencing, but after putting it in drive and starting to drive it sounded like constant squeaking with acceleration, with slower acceleration than usual until it stopped intermittently around 40 mphs, then coming back here and there til i got driving for about 5 minutes, still with slow acceleration til about 40-50mph.

It's been a couple days since, as I honestly have had zero spare time to work on it til now and the acceleration is still slow, crank is sloppy and sounds a bit dry if you know what I mean. Also is the XJ6 supposed to crank so quickly? I feel even before this happened it almost seems like on key turn to engine on it feels almost too quick, starting the engine "prematurely" and sometimes losing rpm and shutting off on a poor crank, I feel like it gets worst as the car gets hot, cold crank is peak.

So I ask as I have a few gaps in my knowledge of exactly what this might be, I've read Parker7's recent right ups on the 94' stalling regarding possibly burning fuel pump relay which I intend to swap tomorrow, as well as try the chevron brand injector cleaner too. I want to check the fuel pressure but I don't have the Jaguar fuel line adapter I read about nor a fuel gauge at the moment. Could also be CKPS as I've never taken a look at it, or did I throw my timing off? Kind of just spitballing with this as I've been self teaching myself as I go over the years since I got my first and it's all youtube and this and without any mentor or person to guide me there's been a lot to find out through experience starting from scratch. Thank you for all you that have continually assisted here and there, I'm taking her tomorrow to get some really nice 90% heat reduction ceramic tint and I'm so excited to finally stop sittin in a fishbowl! Gonna look so pretty I will share pictures later and then tackle any suggestions after my appointment with whatever ya'll got!

edit: sitting here thinking more, I also had a successful start recently that was rough, and a shut off about 15 seconds after startup, and saw some liquid dripping from under the center middle of my car. Could that be from the EVAP Canister? I've had so many odd fuel problems I wouldn't be surprised if I'm still running rich, how do I test for that? Also maybe my coolant sensor is still bad, buying another now, Parker said something about calibration but i didn't see anything about how to on the 801S.

 

The large under the car fans control relay module should be mounted so the connector is on the bottom otherwise it will fill with water , I could shake mine and hear the water , ends up destroying inside module power contacts

If you have the TSB done on the fans they will run in low mode on first rotating ignition key

Going through the rest of your post

 

My relay was faulty too. No low speed fan when AC was on. I was able to reach it from underneath without taking the wheel and wheel well cowling out but it's clipped in to a bracket and I ended up breaking the tab. The used/new relay had the tab already broken off so I zip tied it. My symptom is that the low speed fan didn't work so the AC was not effective after it got above about 75F? The High speed fan would eventually kick in but then turn off after a couple of seconds due to the pressure dropping.

 

The X300 fans control module ( white in color ) and X308( black ) are electrically close but different

there is a test I came up with that test the coolant temp but not the freon pressure aspect

In removing connectors from fan motors the connector lock can break from being old and brittle