MzChromey

I have a 2001 Mustang 3.8L and she's been having some herky jerky issues. At first I feared the transmission, but am wondering if it's the fuel pump. We did replace the fuel filter, and she improved a little bit.

I notice if I'm going up a hill she jerks back and forth slightly. Also on these hot days (90+ degrees) the hesitation is heightend. When I was making a left turn onto the highway, she was doing that herky jerky movement.

We replaced the fuel filter and noticed a slight improvement. It was nice but short lived. Cool day, she's awesome-ish. I'm just lead to believe it's the fuel pump. Feels like there's blockage or air or something that is screwing things up.

Does this sound like the pump or something else?

Derf00

How old are the plugs and plug wires? Might need a fresh set of both. Especially from your description.

Bad wires will allow voltage leaks where the spark actually goes through the wire or boot and goes directly to ground vs through the plug electrode. Any wires that come in contact with the exhaust manifold are more prone to failure due to the extreme heat.

Daehawk

I post this suggestion so much I started to not even post it....have you checked the CATS? They get clogged and can rob power under load and heat.

daddyo4363

Might want to check your ignition Coil also.. Mine was missing and jerking and bucking as well. It finally threw an engine light and it showed misfire.
Turned out the Ignition Coil was bad..

MzChromey

Thank you so much for your help!! We had replaced the coil and spark plugs a couple of years ago. We couldn't remember if we changed the spark plug wires or not. I think we did, regardless we did it again! lol Got Motorcraft this time and they fit snugger than the previous ones. Just got back from a 15 mile test drive (had specific road inclines I wanted to test) and she is wanting to GOOOOOO! No issue! Thank you! Thank you! Thank you!