2000 Rodeo hesitation

Hello,

I'm new here and have got a question before I have an authorized service center look at my Rodeo for this problem. My 2000 4-cylinder Rodeo is hesitating quite often during acceleration. This hesitation is variable - sometimes it happens during acceleration from a stop, sometimes while the vehicle is moving and I upshift.

The check engine light is not on. In the past year, I've replaced the spark plugs, spark plug wires, fuel filter, timing belt and a host of other items listed on the 60k mile service. Also, the fuel pump and sending unit have been replaced within the last 3 months (on my third one of these at this time). When I first started having the problem with the sending unit, it tripped the check engine light, and for about a couple of months I was putting a bottle fuel injector cleaner with each new tank of gas. The fuel injectors should be clean. Thinking about it, this problem seems to have first appeared when this area switched to ETOH as an octane booster. Maybe coincidental, maybe not.

I'm fairly handy with maintenance and if it's something easily replaced, I'd like to do it myself. If it's something big, I'm more than happy to have the shop do it.

So, has anybody got any ideas on where to look? I'm surprised, with the degree of hesitation, that this isn't tripping some error codes (btw, the check engine light does come on and go off during startup as it should, so the light itself isn't nonfunctional). Input is greatly appreciated.