z28 tune up south of england???

[iaiin]

Got my z28 (5.7 1993) & its missing, had loads of service , oil change etc but cant sort this problem out?? Any one know of somebody that can sort it? I live near portsmouth & all my mates, garages etc dont want to know when i say what car it is? There is a rooling road but he has only said he can tell what bhp its making. What happened ti good old krypton tunning!!!!
When i had my dodge some blokes on here told me about some bloke name at portsmouth but lost it dohhhhh.
The bloke i got it of changed the opti spark & it was running fine at first but has started missing now?
cheers Ian