Not sure if this is even relevant to your car.
A similar problem on my '87 260E (KE Jetronic fuel injection) was caused by the coolant temperature sensor. This is a little brass bodied, two pronged, sensor that sits on the back end of my 6 cyl's head. No idea if your car has a similar beastie, but if it does would be worth checking.
Typical test procedure says to check from terminal to terminal. You should get a resistance that varies with coolant temp. Off the top of my head, 3k at 20 C and 100 at 80C, but don't hold me to those numbers. There's a chart floating around. What I found by looking at wiring diagrams is that the sensor is actually two resistors, both with an end at ground and the other end at a terminal. IOW, check from ground to each terminal and look for 1/2 the resistance. One side is for the ignition & the other for the fuel injection. If one side is open, try switching leads as a temporary fix, the fuel is much more sensitive than ignition. a new sensor is about $40.
An open circuit tells the electronics that you're parked in the Arctic & need lots of fuel. You'd need to hold the pedal down to keep from flooding it.
As far as "no testing equipment" goes, Sears sells a meter for $40 that does the usual volts & ohms and also duty cycle for fuel injection.
It helps.