Engine Cold And Has Hesitation and Stumbling issues almost dies out. Only when cold. Once the Engine is at full temp Runs like a Charm. No check engine light. I ran codes aanywa, Nothing there. I bought this car 2 weeks ago. Some history on The car. 175,000 miles . I Just replaced the Transmission with a JDM B7XA. that's Shifting Fine and working well now. Had Some what of an over heating issue. Replaced Radiator and Engine Temp sensors and Fan Switch. That's All doing well now. I replaced Timing belt and Water pump Before all else. That's completed and working well. I replaced All coolant Sensors. Fan Switch, temp Gauge,and engine Temp Sensor as well. Replaced Thermastat with Factory temp. All new hoses and works.
When car is cold, idles Great. Never dies or acts Weird at idle During Warm-up period.
But once I try to excelerate it Falls flat, Coughs, almost stalls out completely. But if I peddle the Throttle, it helps but Engine Takes off Almost uncontrollably. Surges... Weird..... ANY And ALL help is seriously appreciated... Thank you..

 

could be air in the cooling system is freaking out the coolant temp sensor.
had to bleed the hell out of mine after sensor change before it behaved.
squeezing the hell out of the lower rad hose helps a lot.

https://honda-tech.com/forums/honda-...ystem-2637402/

 

It's possible the exhaust is clogged up, normally the cat. You can try removing the oxygen sensor to allow the exhaust to breathe and see if the car runs better. It will throw a code for the oxygen sensor since it won't be plugged in but that's ok so you can see if it runs better.

 

im running a Cat Test pipe as I write this. Exhaust is not the issue..

 

i used an "Air Lift" to run vacuum in Cooling system and That sucks Coolant into all parts of the cooling system. I did it twice. No change. Car still doing same thing. When it a cold start up. Idles great and runs great. Put it into Gear and press the Gas peddle It Couch's, Spudders, almost dies out. Again, I peddle it and Gets Past all the Stambling, explodes with acceleration.. Once the car warms up. Runs Wonderful

 

did you use sealant on the sensors?
i didn't and my problem is back so it must be sucking air through the sensor holes.
not a word about this in the helm manual but haynes and chilton say sealant necessary.
some guy on youtube said no sealant necessary on the ecu ect. guess he's wrong?

 

i used Teflon tape on the sensors.

 

check the valve clearances

 

found the Issue with cold driviablity issues and Dash lights Flashing . after Extreme Amounts of electrical diagnostics . turned Out to be the Old car Alarm Installed was the culprit. Trace to the wiring issues back to the ecu . 3 broken wires or partially broken wires Heading Into 3 different ECU plugs. R/R ECU wiring . now Runs great. Thank you for All your help..