On your cruise control, one of the first checks is to be sure the brake switch and or clutch switch is adjusted correctly, as they will automatically dis-engage cruise if not in the correct adjustment. Let's check the easy stuff first.
The clutch switch is used on vehicles equipped with manual transmission. When the clutch pedal is depressed, the cruise function is disconnected and will remain so after the pedal is released.
Below is the complete diagnostic for the cruise.
When performing the following tests, refer to SCHEMATIC DIAGRAMS/ELECTRICAL AND ELECTRONIC DIAGRAMS for wiring diagram.
This information should get you to your problem. I do agree, sounds like the lever/switch.
I understand. Way back, I had a tester for these I bought from Snap-on, but that won't help you on this one. I know the manual tests are a bit of a pain, but they do give us apretty good set of tests for the switch. I would check the voltages at the lever and see what you come up with.