I have a hesitation very slight hesitation just as I throttle up. I call it a burp and then go. Not all the time though.

I have read several things here about hesitations and have complete most of the checks to find out why.

Throttle body cleaned/new gasket
ICV cleaned
vacuum checks
AMM check
new hose for brake booster check valve
intake hose removed cleaned

The only new thing I have done recently was to replace the exhaust system from the manifold back and I eliminated the resonator and went with the 2" pipe from the kat to the tail with a turbo muffler. Also a new O2 sensor but it was not the exact replacement #. (due to cost I went with #13942 Bosh cut-n-slpice)
Anyway I am now wondering if the burp and go is due to the larger exhaust pipe and I am getting less back pressure. Is that possible? Maybe this was not worth the effert to change to, although I like the tone.

The other items I need to check are FPR and the Fuel pumps. I know the main under the car is working but have not verified the in tank pump is heard.

If I use a FPR gauge to check pressure, how do I connect it to the system?

BTW are FPR that different from another? I found a BWD for 55.00 rather than Bosh for 125.00..

Any other thoughts or rehash on the topic would be of interest.
Thanks
Judd