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There is the hardware of the ECU and then there is firmware and a set of settings for a specific engine size and ECU firmware revision. The firmware has been revised several times (5.2, 7.2, 7.8 are revs numbers that come to mind) and the codes aren't always the same though when I looked this one up I was surprised at how different the meanings of the same P-code were. E-gas versus mechanical throttle activation meant a big revision and they repurposed the meanings of the possible codes I guess..
Which is why my above message suggests that a code always be accompanied by the model year (if everything is stock) or DME firmware revision number so the P-code can be looked up and the list of causes for that DME version can be cited. After all you could have a 97 model year with an engine from another year and a DME that goes with the engine and doesn't match the chassis.
JFP is a guru and he probably looked up the 1502 code in the 5.2 "book" but your Durametric results text implies you have a later 7.2 firmware revision.
When you disconnect the MAF, the engine runs without trying to adapt to what the sensors are telling it. When you reconnect, it takes a while but then adaptation takes place and if you are getting a bad sensor reading the CEL can get triggered because the ECU firmware knows that value just doesn't make sense.
"The position of the throttle is controlled by a digital position controller which emits a pulse-width-modulated (PWM) duty cycle and a direction bit." And the circuit diagram shows a 6 wire connector back to the ECU from what must be a position sensor probably connected to the throttle body. Unfortunately, the ECU manual only speaks of replacing the "throttle part".
Connector, wiring? Any work done near there before the CEL went off the first time?
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