I have an 86 LE and my transmission is sticking in first gear. It sometimes starts to work after warming up and if I can coast at a high enough speed in neutral then shift to drive it will be in a higher gear, but otherwise, it's stuck.

I was also noticing that in the higher gears, if I took my foot off the gas, the rpms would drop down to an idle and with the slightest touch of the gas it would shoot back up.

I had already been experiencing some problems going into overdrive. I checked all the electrical components and couldn't find a problem when it miraculously started working again (although I eventually discovered, only after warming up.)

I changed the transmission filter and fluid, checked the cable that connects to the throttle and it seems to be moving smoothly and easily, and now I'm wondering if there's anything left to check before I have a professional dive into the transmission.

Thanks!