last night i installed a new shutoff valve on the side of the IP. I'm pretty sure i did it right. the car still won't shut off sometimes. what did i miss? are there any other areas i should look into? help!

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$500 1982 240d owner "Gunter"
125k miles,4 speed manual
crank windows, MB Tex, all original
no a/c, daily driver
Scorecard so far....
$230 Maaco paint job
$27 dimmer switch, $40 shutoff valve, $45 brake MC, $260 calipers, $40 brake hoses, $40 side fender trim, $20 balancing, $109 lifetime alignment, $10 fuel return lines, $115 oil&fuel filters for next 30k miles