98 runs lousy when cold. TPS code

My 98 runs lousy when cold, coughs chugs stalls and Engine Service Soon light comes on every morning. I get a code for the throttle position sensor. I have replaced EVERY sensor under the hood including the entire throttle body. (I work at a recycling yard) and I have run ground wires to every part of the engine and wiring harnesses. I have replaced the PCM, the EGR, the entire ignition module the fuel pressure regulator (new) and still the same thing every morning. After the car warms up it runs PERFECT, and about a half hour after that the Engine Service light goes out and the car is good for the rest of the day. The only sensor I have not replaced is the fuel tank pressure sensor (accessible thru the trunk floor). It shares the same 5 volt reference source as the TPS and the EGR.

Any guesses? Am I missing something?

A bad O2 sensor could be to blame.The Aurora has 4 sensors, but they should set a code.
A bad "crankshaft position sensor" will cause a rough running engine, again it should set a code.

My 98 runs lousy when cold, coughs chugs stalls and Engine Service Soon light comes on every morning. I get a code for the throttle position sensor. I have replaced EVERY sensor under the hood including the entire throttle body. (I work at a recycling yard) and I have run ground wires to every part of the engine and wiring harnesses. I have replaced the PCM, the EGR, the entire ignition module the fuel pressure regulator (new) and still the same thing every morning. After the car warms up it runs PERFECT, and about a half hour after that the Engine Service light goes out and the car is good for the rest of the day. The only sensor I have not replaced is the fuel tank pressure sensor (accessible thru the trunk floor). It shares the same 5 volt reference source as the TPS and the EGR.

Any guesses? Am I missing something?

The only code that comes up is the TPS code and Engine misfire!
Again ALL sensors have been replaced with no change in problem

Have you tried to reset the position sensor using the 'idle learn' procedure? Key into switch and turn to full on without starting engine, wait one minute, turn off and remove key.

Unfortunatley I have done this. No cures. What kills me is that it purrs like a kitten once it reaches operating temperature.

Unfortunatley I have done this. No cures. What kills me is that it purrs like a kitten once it reaches operating temperature.
IAT sensor at the airbox or maybe the coolant temp sensor

check for vac leaks

pull EGR and clean it/replace it

did you check/change plugs/wires/coil packs? What about fuel pressure regulator? Hear any noises when the car starts cold...like a whistling noise or anything?

Does anyone know for sure if the 4.0 has a cold start injector or a 'choke' fuel enrichment circuit?

my '97 does the same thing when it is very cold in the morning. I would like to heard from someone who had a cold starting problem and fixed it. I understand some of these cars came with a heater coolant heater, but only as an option. I don't know if they are for sale. I know JC Whitney have a couple of heaters, such as the dip stick heater. they also have one that is suppose to heat and circulate the coolant through the engine.

It was cold outside today, and as usual Aurora didn't want to start. So I took the duct off the throttle body, pulled the flap open(pull the piece on the side of the throttle body back), and I sprayed a little bit of starter fluid in. the car started right up. If anyone want to know an easy way to get the duct back on without wrestling with it. Put the duct back on the throttle body first. Put a little grease or vaseline on the outside bottom of the air filter housing, where the duct slide on. And a little on the bottom half of the duct. rotate the duct to the filter housing, and you will be surprised. Because it will slide right on.

have you found the cause of the hard starting yet ??