Fuel pump on Mercedes rarely goes bad... they are super reliable. So replace
your fuel pump relays. You can buy them cheap online or refurbished one too.
Cooler AC depends on how well the system is charged... stick with R12 for
maximum cooling capacity and charged it to about 35 degree evaporator
temp... the mechanic can read it at their pressure gauge.
The SL probably need a rebuilt control unit... or a resistor pack... you
need to do diagnostic.
Cruise Control can be repaired very cheaply... buy rebuilt amplifier. Go to
mbcoupes.com and look under part supplier for the three vendors... Colorado
one is the best.
Both of your cars has 4 speed tranny. They both starts off 2nd gear. You can
have your tranny serviced to starts off first... but it will cost you money.
Best leave it alone and service the tranny fluid and filter.