I have a 1986 Nissan, 300zx nonturbo, base engine, automatic. I just replaced the starter, and pretty much replaced almost everything in the exhaust system in my car, minus the cat converter. I haven't done any big maintenance with the transmission. It starts and runs fine, until I try to get it to downshift, and it seems like it'll shift but it'll jerk a little and lag behind and then catch itself. Is this a transmission problem, or a fuel-injector problem?

 

Welcome to ZDriver!

First thing to do when you have auto trans shifting problems: check the fluid level and color.

 

I've checked it numerous times, actually. Color is normal, level is also normal. During the winter months, I was leaking trans fluid, and found out the transmission fluid pan had loose bolts, so I tightened them down a bit and that solved that problem, with no more leakage. Possible connection?

 

Also check vacuum lines cause I think that helps it shift Not sure though! But I would drop a 5speed in you will be in heaven. Also could check inhibiter switch, and I think there's a transmission tempeture sensor and a couple other sensors on it! But a 5 speed is the way to go but you do it your self!