Okay, so far I still cannot figure out the "stumble" under load heading up hills, but the other day it was mid 80's out and I was running a bunch of errands in town, cruising down the road about 30mph when the throttle went flat like I suddenly ran out of gas, except the car was still running. I coast to the shoulder thinking it died, when suddenly the gas pedal pressure came back and drive home okay until I pulled into the driveway and shut the car off. It continued to diesel so bad I turned the key back on and it ran fine, tried to shut it off again and an endless diesel so on the key came again. After the third attempt to shut it off it finally stayed off and the car made a nasty fuel smell unlike any smell I ever smelt before. This is a car with a brand new fuel pump and filter, plugs, wires, cap and rotor. Not sure what to do. Until recently this car drove great. The miss or stumble heading up hills or freeway speeds has gotten worse as well as a smooth throttle response, which is why I had the fuel pump replaced. Any other ideas?

 

Carb or TPI? Being a GTA it is more likely a TPI set up. It may be that one or more injectors are dirty and leaking past the seat.

RBob.

 

It's could be I suppose. I ran a tank of gas with seafoam, then a tank with techroline, then a tank of gas with 3M injector cleaner. Cleaned the throttle body and MAF. Not sure if the throttle position sensor could cause that either? Yes it is a TPI setup with the 5.7. I also wonder if the injectors could cause the stumble under load? I will hook up a fuel pressure gauge and monitor while driving but an place you can point me to check would be great!

 

The only way a injected motor can diesel is if an injector is still opening when key off. The smell was from dieseling. You've obviously been chasing a fuel issue with all you've done...

Have the injectors serviced in Dalton Gardons at My Injector.

If that does not fix it and you need help PM me your number, I'm in CDA.

 

I finally had a mechanic buddy of mine hook up a fuel pressure gauge and set it to the windshield and took it for a drive. The fuel pressure was perfect at any speed. He thought it felt more like an ignition problem although didn't rule out an injectors problem. We will start by pulling each plug and inspect each wire.

 

When I resurrected my car about four years ago, it was running fine. I put in some injector cleaner anyway, then I had to replace my multic injectors. The factory injectors are not compatible with most fuel additives. Fuel passes over the coils to cool the injector and the additives lead the injector shorting out by dissolving the insulation.

Get an ohm meter and measure the resistance of all your injectors when the engine is good and cold. Warm it up and then measure again. If you get any readings below about 12 ohms then you should replace the injectors.