I've got a 88 firebird 2.8 that's not running like it should. I changed the lower intake and I cleaned the gunk out from under the old intake. I took the rods and the rocker arms off and soaked them in diseal for 2 days. I put a newer fuel rail on it. Right now it will start an run but a ruff idle witch it all ways had, it won't rev past 4k an should be able to go up to 6k. I've checked the vacuum lines spark plugs plug wires. I have a new cap an rotor on it. I'm wondering if my valves are not set right. Any help would be helpful.