I have a 89 tt only firing on 246. But sometimes 5 will fire occasionally.

I have taken the exhaust pipe of 135 off to rule out clogged cats but seems no difference

I recently changed my valve seals so i thought that a cam may be off by a tooth.
The markings on my belt were wiped off so I had to use the sprocket mark the belt cover mark,
also counted the teeth and seems to be the right amount between all the cams. Could it be one tooth off that is causing this? and if so can I skip the cam back and forth by 1 tooth without hitting any cams.

also did the head gasket a while back so I thought it might be that, but what was really weird is that my compression reading are 1:155 3:160 5:150 2:135 4:130 6:135 I know they are not good but I have no clue how the s*** side is working perfectly

First of all welcome to NICO.

Are you sure that you have the injector and coil connectors in the correct places on bank 1?

How do you know 5 is the one that occasionally fires?

Check if there's any fault code.