Intake manifold seals
No I have not checked the intake manifold seals.
I have now replaced the gas line, the gas return line, and the brake line, replaced gas filter, replaced platinum plugs with bosch w8dc, replaced oil and filter. Replacing these lines was a 6 hr. job, the rear end had to be dropped to get to the gas tank.
Things seem to be getting worse. On cold start (15c or about 60f), no start on first crank of 5 sec.. I can start it on first cold crank if I press down on the gas pedal while cranking. But then the engine races to 1100 rpm, and as I ease-off the gas the rpm drops to 500, and the engine feels like it is missing, rocking, but I apply more gas to prevent it from stalling, it runs smooth at 1100 rpm. I give it gas 2 or 3 times, especially if the rpm drops below 500, to prevent it from stalling. I have put in 2 cans of duralube advanced fuel system treatment in one full tank of gas, and run it 1/8 full.
When she is hot, above 60c, she runs very well. Just a little bit of roughness on idle, a little gentle rocking, hardly noticeable, unless you looking for it. Someone suggested replacing the ignition coil to smooth out this idle problem. I finally got the right coil, and it should be installed in a couple of days.
Any other suggestions? Replacing the seals looks like a very big job!
1989 420 SEL