Running poorly

Girl friends car I have had problems with it for about the last year car will run decent get me to work stuff like that always seem that it has a compression problem. I am not good with auto mechanics. Is the 2.4 liter so I am not sure if it just does not have the power or what it is very weak uphill. I replaced the filter, fuel pump, spark plugs wires, crank position sensor, every sensor that I could think of. Spark plugs are gaped where they need to be, but when the car messes up on me I always check the spark plugs and I always find at least one that looks like it has been smashed together. So now at this time that the car messed up I was still going down the interstate about 65 miles an hour going to work it has a manual two automatic knob shifter so I switch it over I switched it over to manual, I accidentally went into neutral so no big deal I kind of have the car still kind of revving when I went and popped it back into drive as soon as I did that the car just shut down, it did not die out completely started sputtering and then died out on me. I had to get off the interstate I sat there and I waited for about fie minutes it started, but I could not get it to go past ten miles an hour. I also have done the catalytic converter replaced all those which they were clocked at one time, as I said I am not a good mechanic so I checked everything again. One spark plug was also smashed again had to replace it wire coils everything that I can tell the best of my knowledge and with a multi-meter everything is working tore the pipe off of the header just to see if anything was clogged again. That did not help the problem and no clogging anyways. Now I have no power whatsoever it is just sputters and wont stay running whatsoever. It seems after that Interstate incident I did something to mess up the car also as long as I have known we are having this car you would have to kind of let off on the power to make their car shift. I do not know if that has anything to do with it after I get the catalytic converters I got to run up to ninety miles an hour still weak. But like I said 2.4 liter. I do not know if it was just the car or what always be loyal transmission fluid coils of firing checked all fuses, but the guy said the car just better than a run for about a minute and let it cool off for five minutes start it it will run and idle normal, but as soon as I give it gas it sputters and dies out. I am out of ideas. Please help!