Thanks in advance for your help.

No codes.

Drives well cold.

But after a few minutes of driving, when starting from a stop using about 1/4 throttle, the engine will hesitate at around 1,500 rpm for a second (feels like I've let off the throttle), then it surges. Occasionally, I get a "lean pop." It clears up at around 2,000 rpm and runs fine beyond that.

It doesn't happen when I use ½ or more throttle, though. Off-idle response with light throttle is good (like when driving in a parking lot).

I've done the following:
Cleaned the IAC
Set minimum air as instructed on the tech page
Checked the TPS (sweeps through voltage looks good)
Set the TPS to .54V
Cleaned the throttle body
Checked the timing - (it's right-on)
Checked the EGR (and pulled the vacuum line and plugged it - no change)
Replaced the PCV valve
Replaced the Coolant Temperature Sensor (CTS / ECT)
Recent cap and rotor

I'm hopeful its not a time-consuming and expensive fuel pump, injector or fuel pressure regulator issue. But because it seems like a fuel delivery issue once warm (and only happens at about ¼ throttle), I'm thinking it's a sensor issue. I'm tempted to replace the 02 sensor, then the MAP sensor.

But I've thrown good money after bad before, and am really hoping someone can help me out. Could it still be the TPS even though it seems fine? Thoughts on the 02 and MAP? Thanks!

 

Fixed - it was the TPS

Tough to diagnose because it was a very narrow range where it was messing up, so I couldn't identify the hiccup on my digital voltmeter.

For anyone else who is unsure of their TPS diagnosis, I've heard that removing the TPS and testing for resistance in ohms by slowly opening the arm may make it easier to spot a problem.