98GT, runs fine when cold, dies after warm


New Member
Feb 10, 2020
Corinth, TX
Hey y'all, newbie here. My 98gt 4.6 (96 motor) runs well when below normal operating temp. After warm up, It starts to buck after changing gears (all gears) and then dies. Check engine and air bag light sometimes comes on when it happens. I come to a stop, turn off ignition, then turn her back on. All lights clear, but still bucks and dies. Sometimes the lights come back on. I've read some of the threads and ended up replacing the following, to no avail:
Crankshaft sensor and connector, camshaft sensor, plugs, plug wires, both coils, clutch assembly, fuel filter, temp sensor, cooling fan assembly (had busted blade and fan motor locked up), alternator, oil filter housing gasket (massive oil leak), and pulled throttle body and cleaned thoroughly. Not sure what is next. Any ideas are appreciated. TIA
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SN Certified Technician
Aug 14, 2009
Houston Texas
Do you have any idea what the PCM "thinks" the value of:
  • ECT
  • IAC
  • open or closed loop?
  • What about the EGR flow?
Yes you have changed sensors but does that mean the PCM is actually getting the correct answer?

Do you know what the fuel pressure is? Have you checked the low/high speed fuel pump relay?

It would also help to know what the long term fuel trims (LTFT) and short term fuel trims (STFT) are doing.

ForScan ODB2 scanner w ELM327 USB

Here's some information about how important the charging system is.

Howto perform charging system voltage drop test