I have a 1999 Grand Am 3.4l GT. the transmission slips really bad sometimes. Most of the time it runs perfectly. The slipping always happens when going from reverse to drive and the car is hot. I was thinking a linkage problem. The fix when driving is to either pull the shifter all the way into low gear or to stop and put it in park for 5 to 10 seconds. Any ideas?

SOURCE: 2006 Pontiac G6 GTP Transmission Drive Not Working

trans usually coupled (electroically) with engine revs. check computer chip. perform computer diagnostics.

SOURCE: Everytime I put my car i park it goes into reverse.

It sounds like you have a damaged shifter cable.It is an adjustable cable but if it is that far out of adjustment then it is probably damaged. Replace it.

SOURCE: linkage broke on transmission now car will not shift out of drive

driveshaft broke

SOURCE: my 1999 ford taurus wagon (automatic) will not go into gear. it comes out of park, but won't go into drive or reverse...you can just slide the shift on the column...it just slips through without stopp

the same thing is wrong with my ford and they told me it was the trans

SOURCE: 96 grand prix slipping transmission

Once it starts slipping in all gears it needs a kit. You need a hoist to get the thing out and back in. If you are looking for a low buck fix many junkyards will sell you a used one and put it in. They are almost always cheaper than a "Transmission Shop". If you have the tools and want to do it yourself buy a service manual for the car from eBay or Amazon or a former Pontiac dealer and have at it. It's not all that difficult with a hoist but it is still along day.