1991 Accord Help------

i just bought a 1991 accord...it has a custom intake and exhaust on it, as well as a custom catalytic converter

my concerns are

1. the car isnt getting the best gas mileage...maybe 20 mpg on city streets

2. sometimes when i start the car when its cold it doesnt catch right away....sounds rough on starts

any ideas? i just did a new oil change and used a fuel system cleaner but nothing really changed..i thought accords got around 25-30 mpg?

o yea i forgot to add....this is an automatic and when i swith gears from neutral, to park, to brake, to d4, etc...its pretty rough...do i need new tranny fluid? it shifts normal while driving though

gas milage sounds normal, stick shifts get more milage because they can shift sooner at lower RPMs, therefor using less gas.

also doing mods will cause a change in Air/Fuel Ratio and if the computer can't compensate for whatever reason(weak ignition, faulty sensor, ect.) your gas milage will suffer.