1989 Olds Ninty Eight. Pulled codes 26, 27, 28, 29, 31 (un-hooked TCC & test drove so that may be reason for 27-31) & 42 from ECM. Car stalls out after appx. 10-15 minutes of driving. Stalled on test drive, tapped on bottom of fuel tank, re-started, stalled again, tapped on fuel tank and continued test drive. (Fuel pressure normal) No further occurances after this test drive. Operation now appears normal.

Hook it up to a code reader via OBDII for specifics. Tecnically, there is no reason to flash your ECM unless you are using another ECM from a parts car...for say a 1989 Chevy. This ECM was used on the 1989 S-10 truck with the 2.5L four cylinder, the ’89 Camaro with the 5.0L HO V8 and the ’89 Corvette with the 5.7L Tuned-Port V8 engine. The only difference (aside from the vehicle wiring harness pin population) was the PROM. The PROM contains the calibration software for the ECM. Another reason would be to bypass a security locked ECM like a 2001 Pontiac GT which was notorious for shutting off the fuel pump if the security chip in the key lost connection through switched power.

It is difficult to diagnose random problems and it is possible that the service dealer fixed the fault without knowing it. IN checking the mechanic may have pushed wire connections to make sure they were tight, moved the harness to get to the ECM and in doing so fixed the fault. fault codes only read sensors that are out of parameters set by the CPU in the ECM and there are a multitude of other faults that are not recorded

If you are saying it starts and then dies, have you checked fuel pressure again ? Could be the fuel pump relay.

The overdrive solenoid in the transmission locks the torque converter, and at low speeds, if it activates or hasn't released from a high enough speed, it will cause stalling. If that is what's happening, it could be the solenoid, or the signal line to it from the ECM, or the ECM itself not working properly.

CODE PO744 AUTOMATIC TRANSMISSION TORQUE CONVERTER CLUTCH SOLENOID VALVE FAULT. POSSIBLE CAUSE FAULTY TCC SOLENOID.CHECK TCC SOLENOID WIRING FOR DAMAGE.OR YOU COULD HAVE FAULTY TCM OR ECM. IF THE TCC SOLENOID IS FAULTY YOUR ENGINE WILL STALL OUT AT A RED LIGHT OR STOP SIGN.YOUR ENGINE WILL STALL OUT AT EVERY STOP THAT WOULD BE SIGN FAULTY TCC SOLENOID.IF ENGINE DONT STALL OUT THE TCC SOLENOID COULD COULD BE STUCK OPEN, IF YOUR TORQUE CONVERTER FAULTY IT WILL CAUSE PREMATURE LOCKUP STALLING OUT THE ENGINE.

TRY CHANGING FUEL FILTER,COULD BE CLOGGED FUEL FILTER,FUEL PUMP FAILING,FUEL COULD BE CONTAMINATED WITH WATER.IF FUEL SYSTEM OKAY,CHECK FOR SPARK AT SPARK PLUGS,COULD BE FAULTY IGNITION MODULE OR FAULTY IDLE AIR CONTROL VALVE I WOULD HAVE VECHICLE CODE SCAN FIRST BEFORE SPENDING MONEY.

It's the TCC solenoid in the transmission. It is under the pan that is on the side of the transmission.TCC is for torque converter clutch. You can un plug the the wires that go into the front of the transmission until you get it replaced, you just wan't have overdrive. But you can drive it.

The problem is " The Torque Converter Clutch, (TCC) solenoid" is what actually causes the TCC to engage and disengage. When the TCC solenoid receives a signal from the ECM, it opens a passage in the valve body and hydraulic fluid applies the TCC. When the ECM signal stops, the solenoid closes the valve and pressure is vented causing the TCC to disengage. If the TCC fails to disengage when the vehicle comes to a stop, the engine will stall. This is a common problem with older GM vehicles.

What is the status of the timing belt (or chain) on the vehicle? Was it ever replaced by a competent mechanic?

The motor mount needs to be removed to change the belt. The labor guide is 1.5 hours for a trained technician with experience. There is no other way, sorry for the news.