Wont accelerate

[SubieTime]

I have an 08 Impreza 2.5i with 131k miles that I got that had been sitting for at least 4 years cause it needed head gaskets. I bought it, put new head gaskets(and got the heads and block machined flat), timing kit, spark plugs and necessary gaskets and fluids in and it started right up(even with the old gas). It idle and reved normal, however when I went to go drive it, it didn’t run right. It will rev up to about 2-2500 rpm and act like it’s going to die, but then catches itself at about 1k rpm, can’t even get it 25 mph. I thought maybe it could have been because of the gas, so I put in a sea foam and then filled the tank full of premium(3/4 of the tank) and no improvement. There are no engine codes. I don’t want to just throw parts at it as I have already spent quite a bit on it and haven’t found much through research, so any help would be great.
Thank you

 

[garry6913]

First check throttle body and make sure connectors are secure and there is nothing in the intake or air box. Check all your ground wires. Especially the 2 in the front on the intake. Another possible cause would be a clogged converter. That would make it so you can't go over 25 mph.