How can I add more horsepower to my 1994 Honda Accord LX?

[Hebe]

How can I add more horsepower to my 1994 2.2L 4cyl Honda Accord LX without doing a motor swap and saving a bit of money? I have already done an (AEM-V2) cold air intake, an (OBX Racing) headers and a (Borla XR-1 Racing sportsman Oval Muffler) custom cat back exhaust. What else can I do to improve the horse power? I was thinking an ECU upgrade but don't know how much that will help. Another problem I've been having, is sometimes the car has problems starting. Especially after running for a little while and then starting it again. I've replaced the alternator(3x) the battery, the plugs and wires, the ignitor switch, the distributor, rotar button, you name it i've tried it and it just keeps happening. I have noticed that there is a little bit of oil getting into one of my spark plugs and i've replaced the seals but that didn't help much. I figured that was the main problem but it hasn't helped much. I would appreciate some help. Thanks - Hebe