pdbjc--
I appreciate your kind words but I'm sure others know a lot more than I, it's just that I'm more verbose in my answers. What I do know comes from hanging out at forums like this one and another good one,
www.roadfly.org. Also I bought a Bentley's repair manual. Note: The Bentley's covers the E32 chassis, i.e., 1988-1994 7-series BMWs. Your 1995 740iL car is an E38 (1995-2001) chassis, so some things would be different for your car.
Re the spark plug hole to dipstick demo. I've read advice to pull the dipstick and see if the engine is smoking from there as a quick indication of worn rings, etc., so it probably was a valid demonstation. I've been reading up on Bosch fuel injection and it pointed out that on a modern car the dipstick has a seal so it doesn't leak air, which would screw up the fuel-air ratio.
Another thing is that some BMW V8s of that era had a problem with their Nikasil blocks which caused them to loose compression. These blocks were made of an alloy that had some nickle in it which was OK in Europe but in the U.S. the gasolines of those days had higher sulfer contents than the gasolines in Europe and the sulfer in the gas reacted with the nickle in the engine and caused erosion of the cylinder walls and thus caused poor compression and poor performance. BMW replaced many of those engines (and maybe beheaded their chief metallugist). My '93 has a Nikasil engine but I've had no problems but it may have been the problem with yours. Search for "Nikasil" and I'm sure you'll find a better explanation and also the way to identify Nikasil engines by their block numbers. Your new engine could be Nikasil as well. A few months back a refinery in Louisiana made a batch of gas that had a high sulfer content and was sold by Shell. Somehow this destroyed a bunch of car's gas gauges but would have been a problem too with a nikasil engine as well, so find out if your new engine is made of this material and be prepared. Generally speaking though, I believe if an engine is OK to this point there is a small probability of future problems since the gasoline content here in the U.S. has much less sulfer than it used to.
Re performance: With the transmission in Drive my car's performance is so-so since that gear is designed for fuel economy and to make the EPA happy. In sport mode (4th ,3rd, or 2nd selected) the shift points are different and the driving is a lot more lively. Also, Shogun's site,
http://tridem.han-solo.net/auto/erich/auto.htm, has a "reset" procedure and some folks report great improvement following this.
Re wife is no longer engaging in martial relations: Sorry, you're on your own here, hehe.
Re Rows of LED display out. I've heard of this problem. I think the solution is to replace some capacitors which I believe are a part of the main instrument panel display. Search around on the roadfly site for better help.
Re headliner: About half-way down on Shogun's site there is a link about headliners. His site, and the ones he links to, may have good info about the LED problems as well.
Re I lost my job about 3 months after I bought the car... Let's see, your BMW is having problems, you're in the dog house, you lost your job, and you live in Nashville. Maybe you could turn this whole mess into a great country song and make a million. How's your dog doin', by the way? And too bad BMW doesn't make a pickup truck. Just kidding.
Good luck and I hope things improve for you real soon.
--libertylover