COmplete tune up: plugs, cap, rotor, wires, air filter
CLean the throttle body (gasket is like 80 cents) with carb cleaner
Replace oil cap gasket (another $1)
Locate, replace, or re-solder the fuel pump relay. This will leave you stranded. It's under the passenger side of the dash, by the firewall, a white box 1X2 inches. It has a date code stamped on it- replace if over 5 yrs old.
Inspect big air bellows hose for holes while cleaning throttle body.
Look for oil leaks: front engine seals (3), rear main seal, valve cover, transmission tailshaft seal, diferential pinion seal. They're probably ALL leaking some, but if it's bad enough to leave a puddle, it's time to fix things.
Replace the flame trap, holder, and hose ($2.50 from FCP Groton) and clean all other hoses out - more carb cleaner

Inspect front suspension carefully: use a pry bar and check ball joints, tie rod ends inner and outer, wheel bearings, big control arm bushings

Inspect rear suspension trailing arm bushings- if it sags in the back or clunks, they're shot. Cheap parts, but a good hours labor per side to install.

Check all the brakes for wear. Replace any rotors that are warped and any pads that are below 1/2 thickness. (They start out about 3/8 inch thick). Brake replacement is pretty easy on a 240.

Good luck and enjoy your 240.
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE, 91 244: 808K total