1973 450sl idle mystery

[zeggate]

Car starts up fine. Warms up drives fine with slightly lumpy idle. Drove car for about 8 miles to Home Depot and shut her off. After shopping Started car up and she shut off. I adjusted the idle speed screw and drove home roughly 8 miles parked car in driveway and shut her off. After placing items in house returned and started car and she was running rough. I disconnected the airhorn sensor and drove her without shutting off,although the idle is still lumpy. Any ideas, advise or direction is appreciated

[meltedpanda]

from my list of testing for my ever in need of testing Djet system
TROUBLE SHOOTING
Engine Will Not Start, Fuel Pump Inoperative
Check the following: Defective fuse, fuel pump. fuel pump relay, main relay or electrical circuit. Fuel pump relay should click when ignition is switched on and off. Should have voltage from main relay terminal No. 87 to fuel pump relay terminal No. 86. Fuel pump relay terminal No. 85 should have good ground from ECU.
NOTE *Fuel pump operates approximately ½ to 1 second after switching ignition on. Relay is grounded from ECU. Ensure fuel pump operates during cranking.
Engine Will Not Start, Fuel Pump Operates
Check the following: Defective wire to starter terminal No. 50, Manifold Pressure Control (MPC) sensor and/or wiring, temperature sensors and/or wiring. Inadequate pressure in main fuel system, wire connector for distributor contacts disconnected and/or open circuit. Pressure should be 28 psi (2.0 kg/cm2) with starter operating.
Engine Starts, Then Stalls When Cold
Check the following: Defective trigger contacts and/or wiring, MPC sensor or temperature sensors.
Engine Will Not Start Warm
Check the following: Defective thermotime switch, temperature sensors or high resistance at trigger contacts.
Engine Stalls And May Misfire
Check the following: Excessive resistance at trigger contacts, dirty trigger contacts, loose connector, temperature sensors or inadequate vehicle ground.
Engine Runs Rough, White Smoke Comes From Exhaust
Check the following: Injector sticking or connection to injector windings faulty.
Lack of Power
Check the following: Defective MPC sensor, fuel pressure too low, restricted air throttle valve or full-load contact does not close.
Excessive Fuel Consumption
Check the following: Defective sensors, ECU, MPC, improperly adjusted throttle switch or inadequate fuel pressure.
Engine Idles Erratically Between 1000 and 2000 RPM
Check the following: Hose between auxiliary air regulator and intake air distributor disconnected or cracked, throttle valve not closed at idle or idle speed too high.
High Idle, Unadjustable
Check the following: Vacuum leak, injector valve "0" ring leaking or throttle valve out of adjustment.