1988 Jetta cold start

Need some help, 88 Jetta 1.8 digifant fuel system, 175,000 miles
intermitent cold start, turns over but no start. Sits a while
and it will start and then runs fine no hesitation no stalling
gas mileage good. I looked for some sort of cold start injector
but I dont believe this fuel system uses one. It's a 5 speed
and recently replaced starter altenator and ign switch. thanks

Try some of these checks with an ohmeter. On the air flow meter (on air filter housing) test between pin 3 & 4 (1 is closest to the engine & 4 is closest to the air filter) should be 500 - 1000 Ohms, this is the air temp sensor. You can also test between pin 3 & 4 while you move the internal flap & resistance should vary throughout it's range. Also, check resistance on the coolant temp sensor. It's a two pin sensor located where the upper radiator hose connects to the cylinder head, on the underside. It should be a blue connector. Resistance will vary w/temp, about 2000-3000 Ohms @ 68 F or 200 to 400 Ohms at operating temp. Higher resistance at colder temps.

thanks, will test during next no start condition

You can run those checks anytime, usually if the sensor is bad it stays bad or if it's off calibration it stays off. Are you sure you're getting a spark during the no start event?