The PM system is playing up again, won't let me reply. If you have a pdf reader (Adobe Acrobat or similar) or use Firefox the link should work, works for me anyway.
The p/No you quoted relates to the Lambda sensor for a 94-95 940 with a B230FD so isn't the right sensor for your car. That said, i doubt there's much difference electrically as long as the pinouts are the same.
The correct sensor for yours (now you've shared it's a 96 B230FK) is an 0 258 003 381, Volvo P/No 91 35 794 or alternatively, Volvo P/No 91 35 621, Bosch 0 258 003 384, either way subject to you checking the plug is correct, this one should be right :
https://www.ebay.co.uk/itm/VOLVO-940...0/114266609582
Pull fuse #1 before fitting and refit after. It may or may not be your problem though, the fact you've got various mods on your engine could be throwing things out more than somewhat.