NEED HELP with Engine or have to sell

[annette]

I have a 1990 Nissan 240sx 2dr hatchback.I bought it in dec of 2003, It's been a pain in the butt since then. Here's the list of Items I've had replaced.-2 Fuel Injectors-Master cylinder-clutch, pressure plate, throw out bearing-Struts all around- battery-water pump (Twice)about a week after I had the last water pump replaced the car starts running like crap. It has a real rough idle, the whole engine is shaking from one side to the other. It has no power, hesitates, feels like something is clogged then it breaks through a little, runs smooth for a min then back to the clogged feeling. It doesn't run smooth untill you get upto about 85 mph. To change gears you have to have a high RPM or it feels like it's going to shut off. I've taken it to a shop, but I'm in Germany and it's American specs. They want to charge me over 2500.00 to fix. My husband says no way and we will drive it till it falls apart, like it is. I like this car, I've all ready put a lot of money into it. SO I need help.How do I tell if the head is cracked? I'm replacing the spark plugs today. And will replace the fuel filter next. The exhaust system will have to be replaced as well, the welds are broke in several places and it sounds bad. I don't know a lot about cars, just the basics but I need somewhere to start. Any help would be great.

[jab11185]

is the car burning anything? white smoke, black smoke? funny noises.....hard to diagnose without being there.....air filter, oil change, compression check, plug and wires...replace the fuel pump....cap and rotor...there's a ton you haven't done to it that probably should have been done, you've done very little that is engine related considered it isn't running correctly......do an overhaul w/o rebuilding and if that doesn't fix it it's probably internal....that should narrow the problem down a little

but i think you'll have to end up rebuilding this motor or getting a new one...

[Florida240sx]

She said she had exhaust leaks all over...