Recently had my vehicle taken in to get my ECM reprogrammed but still stalling out or not starting at all. Replaced the throttle body, PCM relay, accelerator pedal assembly, and ignition switch. Each time it would run good for 5-15 minutes and stall out or run rough again. Any ideas on what else it could be. Put $900 into parts and labor at this point. Hoping to find out what is going on

 

You should have just posted the codes and saved all that money, for a pair of 70" 4k vizios

 

Let me guess..... are you still using the Crappy Azzed OEM junk Battery Terminal Connectors? First mod to do to every H3/H3T is to replace those garbage connectors with a quality aftermarket set like Stingers or your favorite brand.

 

I had this issue and looked everywhere for the cause / fix. It was all over the place.

What solved it for me is a new catalytic converter which also part of the exhaust manifold. I did get a stainless steel version to help with power, very modest amount to be sure, and the change was immediate. I had replaced the throttle body with the throttle position sensor and it helped only slightly. The catalytic converter replacement was the real fix.

P.S. Thanks to GM making the throttle position sensor an unreplaceable part. It’s molded to the throttle body, unlike any other make I have run across. Doubled the cost easily. Ugh.

 

Oh boy.

 

HOLY COW!
Stainless steel versions "help with power"?

Really?

Can I get 20 more hp with a gold or 40 more hp platinum one then?

 

It’s way more modest than that. Closer to 2-3. On my 2006 Mustang, the increase was closer to 6-9 due to the heavy cast iron stock headers.