"is the 1999 eclipise vaslt superior to the 1990 model?"

The engine in the '90 is a stronger motor. The was a change to the engine
internals in later models; the main bearings caps , rods , and the oiling
system. The result is an engine that sometimes fails because the portion of
the crank bearing that prevents shifting side to side wears out prematurely.
The head, block, crank and oil filter housing/cooler on your 1990 are
superior pieces and are the ones favored by DSM people.
The 1999 car features a stiffer chassis, beter aerodynamics, improved
suspension. It's a better car that's better handling and better looking to
most most people's eyes.
My car is a 1997 awd with the motor from a 1991.
I have combined the best features from several different model years into
one car.

"my brother has the 1990 model brough in 1990, and when i turned 16 it was
given to me and that was in 1999. and that car breaks alot. example, i got
the clicking starter problem, the power steering is leaking, and when it
does, it drips into the alternator which messed it up. i already replace the
engine at 140Kmiles, and the transmission twice. the alternator 2x, the
starter 4x and the power steering onces. and the ECU onces."

It sounds like your brother drove the car hard and maybe did not maintain it
the best.
Starters in these cars seldom fail; this is true for both 1G and 2G cars. 4
starters failing is really uncommon-something is going on there, maybe bad
rebuilds.
Leaking power steering is something I've not dealt with but is an easy fix.
Here's the sad part about the ECU and why us old school guys like to run
into you first.....The ECU fails because three electrolytic capacitors on
the circuit board leak caustic crud. The repair parts cost less than $5.00
and any TV repair guy can fix it in 15 minutes.
It's a common problem but there are intructions on the net and it's
something that most car people could do themselves. The dealers want a lot
for that part.

"lots of problem for the 1st gen eclipse. however, it drive very fast and
can still do 100mph easily."

Very true and that's why many people buy them.
The 4g63 motors in those cars are supported very well by the aftermarket. It
is a very easy engine to work on and there are huge tech databases
maintained by the good people in the DSM community.
You would be shocked to find out how many of us are driving around in 400hp
to 600hp street cars with decent reliability and better that stock fuel
economy.

If you're lucky, Todd will chim in here, he owns both cars and is a very
knowledgable guy.
Until then, you have a lot of reading to catch up on....Start here:
www.dsmtuners.com
www.vfaq.com