Rough Idle and Jerking at Constant Speeds
I posted a similar thread like this in the wrong area I believe. But this time, I have more information and the right thread.
So, to the story! I did an engine swap in my 67 El Camino about 2-3 weeks ago. When I was driving it one time while the engine was still under 100 miles, I felt a light lunge when I was slowing to a stop and the car started to run weird. The idle became quite horrible and shaking the entire car quite badly, and the car would slightly jerk when at constant speeds. Now at first, it seemed like it only did this when in gear. So like in Neutral or Park it would idle normally and not feel like the hood was going to shake off. But more driving would have it happen only once the car fully warmed up and has been driven a good couple miles, and also is now starting to idle rough in Neutral or Park. NOT as bad as reverse and drive mind you, but still quite bad. Transmission is a 2-speed powerglide column shifter, with the GM Crate 250/350 as the new motor.
But I've been doing some troubleshooting and tweaking things here and there and testing out the symptoms. I found a small oil leak from the driver side valve cover that was causing small puddles of oil on the ground. So I fixed that with a new gasket. Problem still persists(I knew it wasn't going to fix it, but it had to be done anyway) I can't find anything disconnected like vacuum hoses, transmission is topped off/a little over full, and the timing is perfect at cold starts and when it's fully warmed up.
My father is convinced that it's the transmission/torque converter going up. Which makes sense, except for the fact that it would be running like crap during cold starts to, right? Or he says a vacuum line is coming loose. But I can't find one anywhere.
Any help is much appreciated everybody!
MORE INFORMATION if needed/wanted: The car runs great at cold starts. It starts right up, runs well, idles well, and the transmission shifts just fine. It's just after the engine has been really warmed up. Like, 5-10 miles warmed up and then it starts running real weird. I will say that it seems to happen faster with a little jerkier peddle usage and on hotter/humid ass days. There is no Transmission fluid leaking from what I can tell. There was some right after the engine swap, but it hasn't since then. Just small oil puddles from the ****ty gasket as mentioned before. But that problem is gone as far as I can tell.
67 El Camino (2sp Powerglide, new 350 crate engine)
13 Malibu(SO COOL! Naw, it's my daily....)
02 Avalanche(Family Truck, passed down to me as my first vehicle. Gone, but not forgotten)