Did the ecu throw a Code 5 BEFORE or AFTER you disconnected that vacuum line?
When you disconnect that vacuum line are you simply disconnecting it? Or are you disconnecting it and plugging the hardline which leads to the throttle body?
Did you follow the step by step procedures in the Helms manual for troubleshooting Code 5?
Have you checked your mechanical timing?
You said you “did” plugs, plug wires, distributor, injectors, and fuel filter. Did you replace all of those things with brand new pieces? Replace them with known good parts from another car? Or did you simply inspect them visually?
If you didn’t start getting a Code 5 till after you disconnected that line then I would expect your problem to be unrelated to the MAP sensor.
Code 5 is specifically due to a vacuum leak in the MAP system. By disconnecting that vacuum line and not plugging the hardline you are essentially creating a vacuum leak. This could cause the ecu to throw a Code 5. Additionally, the vacuum leak would then supply more air to your engine w/o you giving it any throttle. This could be masking whatever your original problem is.
Did you thoroughly check all of the MAP vacuum lines for leaks by either replacing them or pressurizing them with a pump? Even the hardline should be checked. You can check that by bypassing it with a longer vacuum hose if need be.
You’ve been resetting your ECU I assume?
The code seems to be showing up intermittently? Meaning that it doesn’t come on and stay on immediately. Just sorta happens whenever it wants to?
