As Aylad said, the main causes of fast pH rise in a salt pool are:
CYA too low causing the cell to be on too much which aerates the wate which causes CO2 to outgass which causes the pH to rise.
TA too high which over carbonates the water which means faster outgassing of CO2 which means faster pH rise. (Yours is WAY TOO HIGH for a salt pool. Get it down to abougt 70 ppm! It will solve a lot of your problem.)
pH dropped to0 low which converts more bicarbonate (TA) into CO2 (just like putting vinegar on baking soda) which outgasses which causes pH to rise.

Finally, If you keep your FC at about 5% of your CYA level you will probably never need to shock a salt pool. However, if there is a fecal accident or they are urinating in the pool then that is a different matter.
If your testing is showing persistent combined chlorine then a better plan would be to run your FC a bit higher than you are.