Engine

My Porche has had a power drop, often when rpm's drop suddenly as in coming down a hill.  The idle gets rough and smooth acceleration is lost

The only cure is to pull over, restart engine and the car resumes full power

We have checked everything we can think of and fixed it.. ie rotor, wires, fuel pump, gas tank cleaned and filter cleaned etc

We did a smoke test and found numerous vacume hoses were leaking under the intake manifold.. could this be the cause?

Need to replace the motor mounts in my 1988 928 S4. Bought a pair of solid mounts from 928 Motorsports. My Tech is concerned that I might feel too much vibration and might want to look for hydraulic replacement mounts. The Anchor 2698 is available as hydraulic and is referenced as a workable replacement. Would appreciate input here.

I have been having an issue concerning idleing with my 1987 928S4. The car has been driven 82,000 miles.This has been happening for the last 2 years. I am the second owner and purchased the car in 1992 with 24,000 miles. The car is driven in the spring, summer, and fall then put away in the winter. Here's the problem. When I start the car it initially runs fine in every way. As the car warms up and the thermostat rises to approximately the the half way point, the normal operating temprature, the idle starts surging when I am stopped.

I have hit the snag on restoring 928 which I cant resolve. The engine will not start intermittently when hot and driven for a while. The entire engine top was completely redone. All electronics except alternator is new and properly rebuilt and checked, including every sensor and all fuel injectors and cold start valve. Harness checked for continuity. Timing and CO is properly adjusted. Normally the engine performs and start like new. Once in the while it would start and die.  I feels like not all plugs are firing. Smell of raw gas from exhaust is present.

Is there any way to test the lifters in a'85 928 with them and the cams in the car? When I push on the some lifters with a stick they collapse and other don't. They all don't collapse on the same bank. If I find several bad, should I replace them all. The car has 115,000 miles and is my daily driver. Is there anything else in the valve train I should look at?
Thanks
Ed

I have just acquired a 1987 928 S4 and when it was checked out, the technician noticed that there was some coolant on the top of the engine in the V at the front.  Any suggestions as to what that might be and what I should do on that? There is plenty of water in the system and doesnt seem to be a big leak.

Thank you for your help

I have exhausted all my possible avenues on this problem car.. I have been a mechanic for 35 years and have never been stumped like this. the list of repairs is as follows:
compression all good at 175 each
no vacuum leaks whatsoever
has new air flow sensor and injectors have been cleaned and tested
all new plugs and wires, cap and rotor
new temp sensor
new fuel pressure regulators and damper
new green wire

Model: 928, Year:1987, Mileage:108,00, Type of use:Street use only
Where can I get reference to all Tech Bulletins for the 928?I'm doing a top refresh of my 87 (hoses, gaskets, seals, etc) and understand there are some factory Tech Bulletins that I should be aware of, for e.g. one to do with the cam covers.Sincerely,Alex

Model: 928, Year:1982, Mileage:78000, Type of use:Both Street & Track

Model: 928S4, Year:1988, Mileage:69000, Type of use:Street use only