89 Jetta GLI Question

I have an 89 VW Jetta GLI (it has the 1.8 16v motor) that started to act really strange. When I was driving it ran with little power, and to start from a stop you had to smoke the clutch to get it to move. It would only do this randomly. A mechanic told me that it could be the O2 sensor in the cat so I replaced it. It ran perfect for over a month and then all of a sudden it did that same thing again. It doesn't happen everytime I drive it and I have no idea what to do. Please help!

Do you think a brake might be getting stuck on, like from a bad hose? That's my guess since it does it from a stop. Look at the rubber hoses (particularly at the front & see if they're cracking where they bend & attach to metal fittings, that would be a good sign to change them.

No its not the brake system, I have recently redone that. When it is doing this, if you hit the gas, there is a delay and it has a hard time reving up even when i'm not in gear.

How are the maintenance items, filters, plugs, wires, etc...? Does it sund like it's misfiring or sputtering like a dead cylinder or two or is it smooth but just slow?

I haven't really checked all of the maintenance items. That might be a good place to start. It doesn't seem to misfire, it is smooth but it just picks up really slow, kind of like when you are running out of gas. If it were a fuel problem it would have to be the injectors or filters or something because I just had the transfer pump and the main fuel pump replaced.

Start with the filters.

Thanks for the help. I will start there.