I bought an 1988 Z24 2.8L last year previous owners says it had 20000 miles. Looks real clean might be possible. Anyway I've tried looking for a solution to my problem but not having much luck. If I let the car sit a day or two , when I start it up it starts, then stumbles and sometimes stalls. When it recovers it idles high for a second or two then comes down. I have checked the fuel pressure, when I turn the key on I can hear the pump and the pressure is about 42lbs after it runs it's about 37/38 lbs. Also sometimes for the first 20 minutes there is a slight hesitation when I press the gas then seems to go away. I also checked the IAC valve and replaced the air temp sensor in the air filter canister. Any ideas?