Slight hesitation to start at time revs up when.

Have the fuel pressure checked. Also have the trouble codes pulled. Any Advance Auto ro Auto Zone will do this for free.

You could have a problem with the fuel pressure. You might want to test it and see if it is up to spec.
You may have clogged fuel injectors and need to run a few cans of quality fuel systm cleaner to clear the injectors and system out. BG44K is the only fuel system cleaner that really works and I have tried a lot of them. You will have to go to a car dealership parts counter to get it and it is about $20 a bottle. You will use one can in a full tank of gas and you should run two cans with the problems you are having and it will do your engine good anyway as it really removes sludge and carbon buildup other cleaners cannot. You may experience some issues with the engine running funny until you run a third tank of gas after running the two cans of BG44K. This is because it is removing so much contamination it can cause minor port flow issues as contaminants are washed down into the engine oil. You should also change the engine oil after the third tank of gas is gone and by this time you will see an improvement in performance unless there is another persisting issue.
Not having a catylitic converter may cause some issues if you have an oxygen sensor downstream or past it in the exhaust. The oxygen sensor will be expecting exhaust with less hydrocarbons and think that the engine is running rich and send a signal to the computer to give the engine less gas thus causing a lean air/fuel ratio. Also, the oxygen sensor may not throw a code in this situation as it is working within spec, it is just sending the wrong signal due to the dirty exhaust.