Volvo: 91 940 turbo speedometer fluctuation etc., vent lines, vacuum line

Question
Ray,
We were recently given a 91 model 940 turbo sedan. The speedometer and odometer work only sporadically. Usually working after it has been driven for a while. We have noticed a couple of other problems as well. Occasionally we smell a strong gas odor while we are driving. I really haven't paid attention to whether it is during acceleration or deceleration. And when we first start up, if we want to go in reverse, it will stall out unless you keep your foot on the gas while shifting to reverse.

Answer
Meme,
Look at the speed sensor wire at the rear axle make sure they are not broken, fix as needed. If that is not the speedo fix then either the speedo head or the circuit board loose contact, due to poor contacts or corrosion.
Check for broken fuel lines, leak at the pump or filter, lines to fuel rail. Remove the vacuum line to the pressure regulator see if gas comes out. Check the gas cap seal and the boot that surrounds the fill neck. Pull out the trunk liner and see if vent lines from the filler neck are loose or broken.
For the stalling pull off the throttle housing and clean out the built up carbon install a new gasket and see how that works. Using carb spray to remove the carbon build up.