I went to go get my truck smogged and it failed due to high hydrocarbons but only at 2500 rpms.

what’s been done

Plugs
Wires
cap and rotor
coil
2 new o2 sensors before and after cat
fuel pump
fuel regulator
tps adjusted
afm in spec
checked for leaking cold start injector

any ideas what i should check im kinda stuck here

 

1. Fuel mixture issue: Although you've replaced the fuel pump, fuel regulator, and adjusted the TPS, there might still be a fuel mixture problem. Check the AFM (Air Flow Meter) calibration and ensure it's accurate. Consult a repair manual for specific procedures..
2. Ignition timing: Verify that the ignition timing is correct at 2500 RPM. If the timing is off, it can cause high hydrocarbon readings. Check the ignition timing with a timing light..
3. Intake manifold leaks: Inspect the intake manifold and its connections for any signs of leaks. Use a smoke machine or a propane test to detect any leaks..

 

4. Exhaust system leaks: Although you've replaced the O2 sensors, there might still be a leak in the exhaust system. Inspect the exhaust system, including the catalytic converter, for any signs of leaks or damage.
5. Cold start injector issue: Although you've checked for leaking cold start injectors, it's possible that one of the injectors is still malfunctioning. Consider replacing the cold start injector or having it tested.
6. Idle mixture adjustment: Ensure that the idle mixture is adjusted correctly. Consult a repair manual for specific procedures.
7. Vacuum leaks: Verify that there are no vacuum leaks in the engine. Use a vacuum gauge to detect any leaks.

 

Well, high hydrocarbons typically means unburnt fuel.
First, and this is critical in any post, tell us what we're dealing with.

 

Have you checked compression? I had high HC's and it turned out to be a dead cylinder due to a burned exhaust valve (original owner never adjusted valves, 214k miles). This is assuming you have the.3VZE. The original owner drove it almost 2 years on 5 cylinders, the truck ran pretty well in that condition. What a beast of an engine.