My 75 914 1.8 stock won't stay idling. I am not the best mechanic, so let me describe the problem and how it happened and hopefully I can get a recommendation.
The car has original 57K miles on it. I drove to Seattle from Spokane (about 4 hrs) and it drove fine. When I went to fire it up the next morning, it fired up fine but wouldn't idle if I took my foot off the gas pedal. I discovered that the seal on the oil filler cap had gotten loose and was not sealing. Once I tucked the seal back in , voila, everything was fine and it idled just fine. I drove back to Spokane and when I got home, I noticed that there was oil burning all over the top of the motor when I turned it off. I fired it up again and it would not idle again once I took the foot off the gas.
The oil sprayed more towards the insulation on the back of the wall. I am not sure where the oil is coming from. Maybe the black box the filler tube goes into. But if the gasket was blown out, do I have a major problem?
Any advice is very much appreciated.

Get a new gasket ASAP!
Konrad

where are the L-Jet gurus?

L-jet doesnt like it if the oil fill seals are not in good repair. Replace both, they are cheap and easy. Is the cover one still there?

Vacuum leaks are the death of L-Jetronic cars. You will run lean, you will run hot, you will smoke the motor (if you continue to drive it with leaks).

First things first, do as konrad and the doc say: replace those oil filler neck seals ASAP.

Next up for a normal maintainance would be:
1. Replace all vacuum lines with new silicon lines.
2. Set the valves. I like to set them loose, .008" intake and exhaust.
3. Take out the idle adjustment screw on the throttle body, apply a thin bit of teflon plumber's tape, put it back in.
4. Replace and set the points (if necessary). Use bosch points only.
5. Oil change, new filter. Best to do this while you're setting the valves. 10W30 castrol or mobil 1 synthetic are good.
6. Set the timing and the idle speed. You have to do these two together. Idle is 850 ± 50 RPMS. Timing is set as follows: 7.5º Before TDC, Vacuum advance and retard lines disconnected from the distributor and plugged (you will see the mark with a timing light). You may have to turn the idle adjustment screw on the throttle body as you are making timing changes to get them set together right.

I suggested the following service for a few reasons. Mainly because I think you may have all original equipment on your engine. Over 30+ years those cloth-covered rubber lines will break down and cause vacuum leaks in the system (vacuum leaks = bad). It is also nearing your 60k service interval. If you had the trans oil, I'd suggest a tranny oil flush too.

Hope that helps

Thanks for the detailed info Brandon.