Truck hesitates when accerlating

My Girlfriends 99 Ford Ranger had a exhaust leak so I replaced the donut between the catlytic converter and muffler… The noise was gone but when you pull out into traffic… it sputters, and you nearly get killed trying to enter the world of traffic…I thought the exhaust leak would have fixed the problem but it didn’t. The truck looses power going up hills and bucks as it is doing this… Any ideas?

When was the last tuneup done?

By now you may need new plugs and wires, new fuel filter and new air filter.
Those are the easy ones.

The next are harder to fix and cost more.

Perhaps the fuel pump is dying or the fuel regulator is worn out or the injectors may be dirty.

It does run fine once it get’s going… It is just uphills or when accelerating… Should I still replace the plugs , wires , and filters? Thanks…

Yes, you should replace those parts. They should have been replaced as part of the scheduled maintenance. THEN, if the problem is still there, you’ll know it wasn’t those cheaper parts. Next, it could be the throttle position sensor (tps). It tells the engine computer, “Hey, Comp., need more power from the engine.” The computer sends more fuel (by keeping the fuel injectors open longer), and away you go!

Replace the FUEL filter first and see what happens…