Cruise control advice needed

[56weav]

Hello,
I have a 1986 GMC Sierra Classic short bed.
305v8 automatic. With ac , cruise etc.
When I bought this truck 2.5 years ago many things didn’t work and the p.o. wasn’t much of a wrench. That being said the cruise didn’t work , however,
I replaced all the vacuum lines adjusted the servo rod to the carb and it worked.
It had an issue or 2 but worked.
The issues were and are resume didn’t work and it occasionally wouldn’t hold speed up an incline .
One day while messing with the cruise going down the interstate , i tried getting the system to increase speed and the whole system failed. I replaced the control stalk and it worked again however it was still touchy sometimes it wouldn’t hold speed up an incline
And if you disengaged the system it wouldn’t always reengage .
That being said the system failed completely again.
All lines and the check valve, and servo hold vacuum.
Any thoughts out there ?
I am aware and have had new parts fail ( that’s the ac compressor clutch story it lasted 2 days )
Before I do my normal throw parts at it till it works I thought I’d ask
Thank you