True. A Vacuum leak could exist. However I wouldn't normally expect a TPS DTC result from a vacuum leak on these older ECUs. Older cars the ECU lacks the sophistication of newer management platforms and will generally only spit out a sensor DTC when signal falls outside it's normal operating range, such as an open or short. Or an O2 sensor that fails to reach nominal voltage output after a specified amount of time. Back then when an ECU spit a code for a specific sensor it usually meant the sensor or the wiring/VREF is indeed bad.
Newer ECUs after around Y2K became vastly more sophisticated in that they will catch when a sensor reading is 'a little off' for specific driving conditions, and thus a sensor DTC is not necessarily an indication of a faulty sensor, but more of a diagnostic aid in tracing problems which quite often are somewhere else. Bosch was a little ahead of everyone else at that time and this applies to their ECUs going back several more years.
EMS2000, also Siemens product newer than this on a friends' 2000 S40 I looked at a couple months back did *not* catch a bad ECT that was reading -40C when ambient was +25C and a failed TPS whose output was stuck at 0%... but not an open circuit. Bosch and/or anything newer would have caught these for certain.
So... I'm very confident DTCs for these two (TPS & MAP) indicates no or our of range (impossible) signal. I wasn't confident about the brake fluid business, I worded that post as such with a question mark. As I believe the TPS outputs a higher voltage with throttle opening, the sensor signal had fooled ECU into metering gas like crazy (as if WOT) either the ECU VREF internal voltage regulator which is probably supposed to output regulated +5v has failed and sending higher voltage or the violet wire(s) are shorted to +B somewhere in the harness.
As the problem is intermittent, if its running fine and says +5v when he checks it under the hood he'll want to tap one of these violet wires at one of these two sensors with a temporary wire back to a voltmeter in the cabin and watch what it does when the car eventually acts up again.
Edit: It also occurred to me, if the MAP is a piezo resistive element (likely) it may have physically degraded internally shorting VREF to ground and/or it's output to VREF. As this would interfere with 2 sensors at the same time the ECU can't cope/goes haywire. This was the case with that 2000 S40 with 2 bad sensors ECT and TPS: racing idle @ 3000 rpm. Friend discovered on his own if he unplugged the IAC the idle would return to normal. He tried replacing the IAC. When that didn't work and his scan tool showing no DTCs he asked me to come over with the VIDA.
153k
, but I'll try to find a way to make one, lol.