I have recently bought a 1986 Blazer with a 383 engine and a relatively high compression ratio. When I bought it, it came with NGK V-power plugs and they were looking a little fouled so I replaced them yesterday. I put in 8 A/C Delco R43TS plugs. However I am beginning to think those may not be the right plugs, because it is not starting easily and the RPMs are surging a bit. What brand/type of spark plug do you suggest for my setup?