Mitsubishi Repair: Cruise problems and gas consumption, gas milage, gas consumption

Question
92 Galant GS manual 5 speed.
I have been having problems for the past few month's but is has gotten extremly worse these past few days. When driving the car when trying to just cruise on a straight flat road the engine jerks like it looses power for a second almost like hitting the throtle and coming off it real fast.  It now does this all the time, however when I hit the gas to accelerate it has no problem with pick-up at high speeds.  From the stop and go sometimes it feels like the engine boggs down and then suddenly goes.  Since this has started my gas milage has gone in the toilet like I said before it has really gone bad this week, I have not filled up yet but I think since this has started my gas milage has gone from around 27 MPG to about 17 MPG.  I can hear no funny sounds coming from the engine and the tach does not jump around during power lose.  When it started I changed the plugs and wires hoping it was something in there but again this has not helped and it is only getting worse.


Answer
Bill,
This problem usually occurs with either bad spark, bad fuel supply, and/or bad timing.  If replacing your spark plugs and plug wires didn't help, you should have your ignition coil inspected.  Else, you should also have your fuel system inspected.  Test the fuel pump to be sure it operating properly and replace your fuel filter because it may be clogged.

One of the most critical items you should have inspected is your timing belt.  If your timing belt has not been replaced within the past 45k-60k miles, you should have it replaced.  

The last thing I can think of is your car's computer.  Read this article for more information:
http://www.90gsx.com/eclipse/cap/caps.htm

Have your ECU inspected for damage.  It may need to be replaced.
Good luck!