This happened out of the blue.I went to start it today and will with start no problem then fall flat on its face unless you hold the gas. There is no sputtering or anything. I found after a few restarts the car would hold idle on its own but the next time I shut it off it did the same thing again.

Any ideas?

 

If the system is stock, the cold start injector will administer a bit of starting fuel on that initial start. If pressure is low or injectors are not flowing properly the engine might fire quickly but not maintain an idle. Is fuel pressure at least 37 PSIG?

Idle air is also important, so a clean TB and clean/operating IAC system are necessary.

When the throttle is held open the TPS voltage is also increased. Is the TPS at least 0.48V in the closed-throttle position?

Once the engine reaches operating temperature, does it run normally?

Are there any error codes?

 

Got code 34 which turned out to be MAF sensor. Then I did the diagnosis through a chart posted on the net which gave me code 33. Based on that it says to replace the MAF sensor. Fuel pressure and injectors all checked out fine. I noticed a big split in the airbox right in front of the MAF connection maybe this cause the problem.

 

After clearing those codes they never came back. I think the weird starting triggered the maf to throw a code. I cannot for the life of me figure out what is wrong with this car.It runs great and has tons of power but when coming to a stop it will drop idle and die.

Tried a brand new TPS.
Pulled the IAC and it was like brand new
Tried another ECM
Searched for vac leaks with carb cleaner and found none.
After I cleaned the throttle body out a bit with carb cleaner it will hold an idle in park at 3-400rpm. If I disconnect the second vac line on the plenum above the fuel pressure regulator it will hold an idle a little better.

The only thing I noticed when doing a fuel pressure test was when the car shuts off it drops to ZERO immediately. This car has always had a fuel smell coming from somewhere up front but with no leaks anywhere.

 

theres a thing in the tank that connects the fuel pump to the sending unit .its called a "pulsator" they commonly rot. and if you have fuel pressure that drops to zero immediately. I suspect that MAY be your problem.

 

I will check that out. I forgot to mention the only way I can get this car to even start is to hold the gas pedal down a bit.

 

For future reference if anyone has these symptoms. I was only throwing a MAF code on and off because of the way I had to start the car by manually holding the gas down and then it stalling. Do not be fooled into thinking code 34 is actually the problem. This was a very frustrating issue.After changing the injectors which were originals ,checking the pump assembly which was like brand new,changing the MAF relays, trying other TPS sensors the car still wouldn't hold idle. So I decided to swap out the throttle body. Went to the bone yard and picked up a used one and she fired right up and held idle perfect.

Turned out to be a faulty IAC which was changed not too long before I got the car. Was gold and in brand new condition but the pin was stuck all the way forward. There was no SES light throwing this code. Installed the used one back in my original Throttle body and she runs great.