car is a 1989 245DL

hey guys, happy belated turkey day!

I've been meaning to post this issue up regarding my tranny. In the past month it seems that my REVERSE gear is acting weird. I noticed that after driving, my car has difficulty in reversing. The car will act like it's low on gas or something when I shift to reverse. Normally, the car will automatically move backwards without any gas. However, when I shift to REVERSE, the car will not move unless I step on the gas. But it will shake and buck when I let off on the gas and brake. Sometimes it won't even engage in REVERSE, and the engine just revs. For the most part, the car will reverse, but I usually have to gas it. Especially in the morning, or when the car has been sitting for a long time, the car will engage REVERSE easily and will reverse normally without any gas. Is my Reverse gear on its way out? All the forward gears are fine. Yes, I have checked the ATF, and it seems fine in both smell and condition. Anyone know what the culprit is? Could it be the tranny or engine mounts? My theory is that maybe the engine mount is giving out and thus making the engine/tranny alignment out of sync--maybe? I think I do need new engine mounts based on the oil-filter finger test where you put your index finger between the oil filter and the rubber mount below it. My finger is way too snug between the two. There is no play room for my finger at all. Well, even if the mounts are not the source of the problem, I plan to replace them anyway. How much does it cost to replace the engine mounts?