Several days ago I bought a 1992 Mitsubishi Mirage. It's exactly the same car with the same size engine as my 1991 Dodge Colt so I know how it's supposed to perform. The Mirage lacks power when accelerating suddenly, like from a dead stop into traffic (dangerous) and also from 55 to a faster speed on the freeway. I just had a full tune up thinking this might be the problem and but it didn't help.
Uh oh. I'm not a mechanic but had the same problem. I ended up having to get my transmission rebuilt. If you have funny colored smoke out from your tail pipe it could be cataltyic converter. It does sound like the transmission though. If you check early maybe they can fix it before it becomes a very expensive problem.
First, catalytic has nothing to do with causing smoke to come out the tail pipe and second, if it was the the transmission the engine would rev up but you would feel the transmission slipping. So your problem is neither of those two.
It sounds like the engine is starved for gas when you accelerate. This may not show up when the car is in neutral and you rev the engine because there is no load on the engine. The problem could be anything from replacing the gas filter to a faulty fuel pump and every thing in between. I would take it back to the garage and have a mechanic go for a test drive with you and see if they could pinpoint the problem. Just be careful when the guy says it MIGHT be this. In that case he doesn't know either.
Try changing the gas filter. If it is partially plugged your car can "bog" down under acceleration. It is an often overlooked and inexpensive to fix problem. If your car had old gas sitting in it for a long time there is probably dirt and gunk in the system.
Could be your engine is already tired. You know, compression is not the same anymore.
The compression was checked & it's fine. The car sat for months (& who knows how many) before I bought it, so I bet the injectors were REALLY gummed up. I've pretty much fixed the problem by running mostly Premium gas in it & also 3 tank loads of fuel injector cleaner in the tank. It runs MUCH, much better now! But I've found that if I accidentally turn on the air-conditioner, the car's power REALLY screws up even worse than before the fuel cleaner. So lets hope I never need to use the air conditioner!
But now my REAL problem is I'm going to need a head gasket because I can see oil leaking out of the sde of the bottom of the motor in the seal area. I had a mechanic check it & he said it's a leaky head gasket. <YIKES! $$$$ might as well buy another car!!!> I find it strange that even though I'm going through about a quart of oil a month (by leaking) that the compression is still good... I guess that's because the rings are still okay, Huh?...