bucking/surging

[mjs4002000]

I have a 95 Chevy Lumina with the 3.1. Approximately 3 months ago it started bucking/surging when going down the highway and up hill where I had to lightly touch the gas to keep a steady speed. I added some fuel injector cleaner and it cleared right up. That lasted for about a month then it started all over again only a little more frequently so I replaced the fuel filter, it ran great again for about a month, now it has started up again with the bucking and surging, I have added different brands of fuel injector cleaner and replaced the fuel filter again 3 weeks ago with no improvement. It doesn’t do it all the time. When I accelerate lightly from a stop it seems to be OK but if I press hard on the pedal it seems to hesitate, then start bucking while I’m getting up to speed. Once speed is reached it seems to run fine. Other times it won’t do it at all under hard acceleration then 10 minutes later it will. I have a very tight budget and just don’t have the money to start replacing parts. The check engine light has never come on either. Does anyone have an idea of how to narrow it down as to what might be wrong? Could it be that my injectors are just really plugged? Email is [email protected] Any help would be greatly appreciated. Thanks