The problem is not putting the boot over the connector but the other side that cover the wires. Connector is over 1/2 inch, wire end is less that 1/4 inch to go over wire cover tightly.
This is aggravated with the throttle connector 1 inch and has multiple wires, cable end is 1/4 inch.
If you have never seen a d jetronic harness, I can send pictures