15 MIN DRIVING CAR BOGGS DOWN LOSING POWER

could be the alternator.

Errr..why do people post like that?.. Classic Diesel is do not have an electrical ignition system. Once a Diesel is started, u could stick a crowbar through the alternator & recycle the battery for all the difference it would make.

Try cleaning out the banjo fitting for ur Alda, that often perks them up ( http://dieselgiant.com/mercedesaldaboostsystemservi.htm ). Another thing u should check is the crankcase ventilation tube. Over the years, this tube can become blocked with goop.Believe it or not, u can actually stall the motor by holding ur thumb over the vent hole.

the valves may need to be adjusted the cold setting is 0.04'' intake & 0.13'' exhaust [suspect tight valves r not fully closing after engine starts to warm up] this will lead to burnt valves & expensive repair if not addressed. also in addition to A.W.B.T is answer there is a boost control solenoid in line w/ boost diaphragm that clogs up [they do not like to be cleaned & at retail is only about 70.00 dollars] one last note even if primary & secondary fuel filters r new u may still have a fuel starvation problem drain fuel tank into a safe container[no smoking or unshielded lamps] & remove large bung on fuel tank [where fuel supply line comes out] this will expose a coarse mesh filter screen that gets blocked with diesel algae- clean it with carb cleaner spray & compressed air & reinstall & use a bio-stat additive periodically to prevent recurrence, if this is blocked the primary & secondary filters must be replaced as well, unless they r brand spanking new. good luck hope these items help.

Could be you need to do a few oil changes for clean up the motor, or the Turbo may be going bad(if it is a Turbo)

Fuel filters,and fuel screen in tank.Both easy fixes.Try running algae killer for marine diesels.hobbob,and anywhere are right too.These are all maint. items.

Please get your fuel pump calibrated,injector nozzles pressure tested.This could be one of the reasons to loose power.

Had something like this happen to my W140 S350. Seems a few sensors in the system were clogged and would tell the turbo it was over boosting and to open the waste gate to relieve the pressure. It would work fine for the first few miles but as soon as it warmed up it was a slug. You need a good diesel man to run trouble shooting.