Throttle surging under acceleration

[Brian VT]

I just got this 2000 PF. It idles perfectly. No dash lights, no codes.
I drove it to work today. When accelerating uphill I noticed a very slight surging (or faulting?) of the engine. Very slight. A passenger wouldn't notice it. The OBD doesn't show fuel pressure so I can't check/monitor that.
Any ideas what might cause that? Let's start with the cheap fixes first, please.
On a side note (may or may not be relevant), I sometimes smell fuel after driving it. My nose leads me to the fuel filler door. The records from the previous owner show the filler tube having been replaced.

[MisterH]

Since you're showing no error codes and the running condition is stable you might take a look at the MAF sensor. A problem there can cause wild swings in RPM's under various load conditions. There's a possibility the sensing wire is dirty and it can be cleaned (gently!) with MAF spray cleaner. If it were out of spec and sending an incorrect voltage due to it being faulty or perhaps a problem with the harness connector it would generate an ECM error.

[Brian VT]

Thanks. Will check it out.

[Brian VT]

Nope. That didn't have any effect. It looked clean but I sprayed it anyway.
Any other ideas?
It's not a big deal. It's almost unnoticeable. I doubt many people would even feel it but it still bugs me.