A4LD having slipping issues.

[ScottB]

Hello this is my first time posting here but i know there are some great people on here who can help me.
I have a 1990 Ranger with 12,000 miles on the motor and tranny.
I noticed a few days ago when I was on my way home it started to kind of jerk and the tachometer was jumping not to the red line but it was just a little bit to notice. Ever since then it has been getting worse, when i am on a hill or or in a residential neighborhood it will feel like the gears are slipping going into 4th? i think or it just looses it completely and ends up going into over drive. So what can it be? i look at the fluid and it looks fine. I've read saying it can be a vac leak and there was nothing there. The frustrating part is it wont do it all the time!! only when it feels like it seems. so before I hurt my wallet and send it to a mechanic and to find out its something i could have done my self. Can someone help me?

 

[tonyjklh]

What speed are you usually going when this happens?
What gear or gears does it do it in?
Just recently my trans that I just rebuild in Feb started doing that.
Mine was because the wire connection to it was corroded so all the vibrations and bumps would make it jump in and out of overdrive, since overdrive is electronically controlled

 

[ScottB]

It will vary the speed it does it when i go up hill or in the city.
I saw 2 of my spark plugs were loose in the hole so i tightened them, they were so loose i tapped the end of them and they moved. I heard anything to do with ignition will cause an A4LD to act weird.